diff --git a/test/utils.sh b/test/utils.sh
index 826efeb..2127758 100644
--- a/test/utils.sh
+++ b/test/utils.sh
@@ -270,6 +270,28 @@ extract_unique_bundles_from_catalog() {
   echo "$RENDER_OUT" | tr -d '\000-\031' | jq -r "$jq_unique_bundles"
 }
 
+# Given output of `opm render` command and package name, this function returns
+# all related images for the given package in the catalog
+extract_related_images_from_catalog() {
+  local RENDER_OUT="$1"
+  local PACKAGE_NAME="$2"
+
+  if [ -z "$RENDER_OUT" ]; then
+    echo "Missing 'opm render' output for the image" >&2
+    exit 2
+  fi
+
+  if [ -z "$PACKAGE_NAME" ]; then
+    echo "Missing package name" >&2
+    exit 2
+  fi
+
+  # Jq query to extract related images from `opm render` command output
+  local jq_related_images='select( .package == "'$PACKAGE_NAME'" ) | select(.schema == "olm.bundle") | select( [.properties[]|select(.type == "olm.deprecated")] == []) | ["\(.relatedImages[]? | .image)"]'
+  # flatten the lists into one and determine the unique values
+  echo "$RENDER_OUT" | tr -d '\000-\031' | jq "$jq_related_images" | jq -s "flatten(1) | unique"
+}
+
 # Given output of `opm render` command and package name, this function returns
 # unique package names in the catalog
 extract_unique_package_names_from_catalog() {
@@ -359,6 +381,87 @@ get_unreleased_bundle() {
 
 }
 
+# This function will be used by tekton tasks in build-definitions
+# It returns a list of unreleased related images as indicated in a FBC fragment.
+# It compares the provided FBC fragment against the corresponding production index image
+get_unreleased_fbc_related_images() {
+  # FBC fragment containing the unreleased bundle
+  local FBC_FRAGMENT=""
+  local INDEX_IMAGE="registry.redhat.io/redhat/redhat-operator-index"
+
+ get_unreleased_fbc_related_images_usage()
+  {
+    echo "
+  get_unreleased_fbc_related_images  -i FBC_FRAGMENT [-b INDEX_IMAGE]
+  " >&2
+    exit 2
+  }
+
+  local opt
+  while getopts "i:b:" opt; do
+      case "${opt}" in
+          i)
+              FBC_FRAGMENT="${OPTARG}" ;;
+          b)
+              INDEX_IMAGE="${OPTARG}" ;;
+          *)
+              get_unreleased_fbc_related_images_usage ;;
+      esac
+  done
+
+  if [ -z "$FBC_FRAGMENT" ]; then
+    echo "Missing parameter FBC_FRAGMENT" >&2
+    exit 2
+  fi
+
+  # If the index image is provided and has a tag, remove it.
+  # The target ocp version is determined from the fragment
+  if [[ "$INDEX_IMAGE" == *:* ]]; then
+    INDEX_IMAGE="${INDEX_IMAGE%%:*}"
+  fi
+
+  #Get target ocp version from the fragment
+  local ocp_version
+  if ! ocp_version=$(get_ocp_version_from_fbc_fragment "$FBC_FRAGMENT"); then
+    echo "Could not get ocp version for the fragment" >&2
+    exit 1
+  fi
+
+  # Run opm render on the FBC fragment to extract package names
+  local render_out_fbc unique_bundles_fbc package_names
+  if ! render_out_fbc=$(opm render "$FBC_FRAGMENT"); then
+    echo "Could not render image $FBC_FRAGMENT" >&2
+    exit 1
+  fi
+  package_names=$(extract_unique_package_names_from_catalog "$render_out_fbc")
+
+  # Run opm render on the index image
+  local render_out_index unique_bundles_index tagged_index
+  tagged_index="${INDEX_IMAGE}:${ocp_version}"
+  if ! render_out_index=$(opm render "$tagged_index"); then
+    echo "Could not render image $tagged_index" >&2
+    exit 1
+  fi
+
+  # Get unique bundles for each package from the fragment and the index
+  for package_name in $package_names; do
+    related_images_fbc+="$(extract_related_images_from_catalog "$render_out_fbc" "$package_name")"$'\n'
+    related_images_index+="$(extract_related_images_from_catalog "$render_out_index" "$package_name")"$'\n'
+  done
+
+  # Ensure that the jq arrays are flattened and unique
+  related_images_fbc=$(echo "$related_images_fbc" | jq -s "flatten(1) | unique")
+  related_images_index=$(echo "$related_images_index" | jq -s "flatten(1) | unique")
+
+  # Get the images that are only in the fbc fragment
+  local unreleased_related_images
+  unreleased_related_images=$(jq -n --argjson released "$related_images_index" --argjson unreleased "$related_images_fbc" '{"released": $released,"unreleased":$unreleased} | .unreleased-.released')
+
+  # output as json array
+  echo -n "${unreleased_related_images}"
+
+}
+
 # This function will be used by tekton tasks in build-definitions
 # It returns a list of labels on the image
 get_image_labels() {
diff --git a/unittests_bash/test_utils.bats b/unittests_bash/test_utils.bats
index d9f2ebd..046e46c 100644
--- a/unittests_bash/test_utils.bats
+++ b/unittests_bash/test_utils.bats
@@ -37,6 +37,9 @@ setup() {
         elif [[ $1 == "inspect" && $2 == "--no-tags" && $3 == "--raw" && $4 == "docker://valid-fragment-fbc-success-2" ]]; then
             echo '{"annotations": {"org.opencontainers.image.base.name": "registry.redhat.io/openshift4/ose-operator-registry:v4.20"}}'
             return 0
+        elif [[ $1 == "inspect" && $2 == "--no-tags" && $3 == "--raw" && $4 == "docker://valid-fbc-fragment-isolated" ]]; then
+            echo '{"annotations": {"org.opencontainers.image.base.name": "registry.redhat.io/openshift4/ose-operator-registry:v4.15"}}'
+            return 0
         else
             echo 'Unrecognized call to mock skopeo'
             return 1
@@ -45,12 +48,17 @@ setup() {
 
     opm() {
         if [[ $1 == "render" && $2 == "valid-fragment-fbc" || $1 == "render" && $2 == "valid-fragment-fbc-success" || $1 == "render" && $2 == "valid-fragment-fbc-success-2" ]]; then
-            echo '{"invalid-control-char": "This is an invalid control char \\t", "schema": "olm.package", "name": "rhbk-operator"}{"schema": "olm.bundle", "package": "rhbk-operator", "image": "registry.redhat.io/rhbk/keycloak-operator-bundle@my-sha", "properties":[]}{"schema": "olm.package", "name": "not-rhbk-operator"}{"schema": "olm.bundle", "package": "not-rhbk-operator", "image": "registry.redhat.io/not-rhbk/operator-bundle@my-other-sha", "properties":[]}'
+            echo '{"invalid-control-char": "This is an invalid control char \\t", "schema": "olm.package", "name": "rhbk-operator"}{"schema": "olm.bundle", "package": "rhbk-operator", "image": "registry.redhat.io/rhbk/keycloak-operator-bundle@my-sha", "properties":[], "relatedImages": [{"name": "foo-bar", "image": "registry.redhat.io/foo/bar@sha256:my-bar-sha"}, {"name": "foo-baz", "image": "registry.redhat.io/foo/baz@sha256:my-sha"}]}{"schema": "olm.package", "name": "not-rhbk-operator"}{"schema": "olm.bundle", "package": "not-rhbk-operator", "image": "registry.redhat.io/not-rhbk/operator-bundle@my-other-sha", "properties":[], "relatedImages": [{"name": "foo-baz", "image": "registry.redhat.io/foo/baz@sha256:my-sha"}]}'
             return 0
+        elif [[ $1 == "render" && $2 == "valid-fbc-fragment-isolated" ]]; then
+            echo '{"invalid-control-char": "This is an invalid control char \\t", "schema": "olm.package", "name": "rhbk-operator"}{"schema": "olm.bundle", "package": "rhbk-operator", "image": "registry.redhat.io/rhbk/keycloak-operator-bundle@my-sha", "properties":[], "relatedImages": [{"name": "foo-bar", "image": "registry.redhat.io/foo/bar@sha256:my-bar-sha"}, {"name": "foo-baz", "image": "registry.redhat.io/foo/baz@sha256:my-sha"}]}'
         elif [[ $1 == "render" && $2 == "valid-operator-bundle-1" ]]; then
             echo '{"schema":"olm.bundle", "relatedImages": [{"name": "", "image": "quay.io/securesign/rhtas-operator:something"}]}'
         elif [[ $1 == "render" && $2 == "registry.redhat.io/redhat/redhat-operator-index:v4.15" ]]; then
-            echo '{"schema": "olm.package", "name": "rhbk-operator"}{"schema": "olm.bundle", "package": "rhbk-operator", "image": "registry.redhat.io/rhbk/keycloak-operator-bundle@random-image", "properties":[]}{"schema": "olm.package", "name": "not-rhbk-operator"}{"schema": "olm.bundle", "package": "not-rhbk-operator", "image": "registry.redhat.io/not-rhbk/operator-bundle@not-my-other-sha", "properties":[]}'
+            echo '{"schema": "olm.package", "name": "rhbk-operator"}{"schema": "olm.bundle", "package": "rhbk-operator", "image": "registry.redhat.io/rhbk/keycloak-operator-bundle@random-image", "properties":[], "relatedImages": [{"name": "foo-baz", "image": "registry.redhat.io/foo/baz@sha256:my-sha"}]}{"schema": "olm.package", "name": "not-rhbk-operator"}{"schema": "olm.bundle", "package": "not-rhbk-operator", "image": "registry.redhat.io/not-rhbk/operator-bundle@not-my-other-sha", "properties":[], "relatedImages": [{"name": "foo-baz", "image": "registry.redhat.io/foo/bar@sha256:my-bar-sha"}]}'
+            return 0
+        elif [[ $1 == "render" && $2 == "registry.io/random-index:v4.15" ]]; then
+            echo '{"schema": "olm.package", "name": "rhbk-operator"}{"schema": "olm.bundle", "package": "rhbk-operator", "image": "registry.redhat.io/rhbk/keycloak-operator-bundle@random-image", "properties":[], "relatedImages": [{"name": "foo-bar", "image": "registry.redhat.io/foo/bar@sha256:my-bar-sha"}, {"name": "foo-baz", "image": "registry.redhat.io/foo/baz@sha256:my-sha"}]}{"schema": "olm.package", "name": "not-rhbk-operator"}{"schema": "olm.bundle", "package": "not-rhbk-operator", "image": "registry.redhat.io/not-rhbk/operator-bundle@my-other-sha", "properties":[]}'
             return 0
         elif [[ $1 == "render" && $2 == "registry.io/random-index:v4.20" ]]; then
             echo '{"schema": "olm.package", "name": "rhbk-operator"}{"schema": "olm.bundle", "package": "rhbk-operator", "image": "registry.redhat.io/rhbk/keycloak-operator-bundle@random-image", "properties":[]}{"schema": "olm.package", "name": "not-rhbk-operator"}{"schema": "olm.bundle", "package": "not-rhbk-operator", "image": "registry.redhat.io/not-rhbk/operator-bundle@my-other-sha", "properties":[]}'
@@ -206,7 +214,7 @@ setup() {
 }
 
 @test "Get Unreleased Bundle: valid-fragment-fbc-success and index with tag" {
-    run get_unreleased_bundle -i valid-fragment-fbc-success -b registry.redhat.io/redhat/redhat-operator-index:v4.27@randomsha256
+    run get_unreleased_bundle -i valid-fragment-fbc-success -b registry.redhat.io/redhat/redhat-operator-index:v4.15@randomsha256
     EXPECTED_RESPONSE=$(echo "registry.redhat.io/rhbk/keycloak-operator-bundle@my-sha registry.redhat.io/not-rhbk/operator-bundle@my-other-sha"  | tr ' ' '\n')
     [[ "${EXPECTED_RESPONSE}" = "${output}" && "$status" -eq 0 ]]
 }
@@ -217,6 +225,48 @@ setup() {
     [[ "${EXPECTED_RESPONSE}" = "${output}" && "$status" -eq 0 ]]
 }
 
+@test "Get Unreleased FBC related images: missing FBC_FRAGMENT" {
+    run get_unreleased_fbc_related_images
+    EXPECTED_RESPONSE='Missing parameter FBC_FRAGMENT'
+    [[ "${EXPECTED_RESPONSE}" = "${output}" && "$status" -eq 2 ]]
+}
+
+@test "Get Unreleased FBC related images: invalid-url" {
+    run get_unreleased_fbc_related_images -i invalid-url
+    EXPECTED_RESPONSE='Could not get ocp version for the fragment'
+    [[ "${EXPECTED_RESPONSE}" = "${output}" && "$status" -eq 1 ]]
+}
+
+@test "Get Unreleased FBC related images: invalid-fragment-fbc" {
+    run get_unreleased_fbc_related_images -i invalid-fragment-fbc
+    EXPECTED_RESPONSE='Could not render image invalid-fragment-fbc'
+    [[ "${EXPECTED_RESPONSE}" = "${output}" && "$status" -eq 1 ]]
+}
+
+@test "Get Unreleased FBC related images: valid-fragment-fbc and invalid index" {
+    run get_unreleased_fbc_related_images -i valid-fragment-fbc
+    EXPECTED_RESPONSE='Could not render image registry.redhat.io/redhat/redhat-operator-index:v4.12'
+    [[ "${EXPECTED_RESPONSE}" = "${output}" && "$status" -eq 1 ]]
+}
+
+@test "Get Unreleased FBC related images: valid-fbc-fragment-isolated and missing index" {
+    run get_unreleased_fbc_related_images -i valid-fbc-fragment-isolated
+    EXPECTED_RESPONSE=$(echo "[ **\"registry.redhat.io/foo/bar@sha256:my-bar-sha\" ]" | tr ' ' '\n' | tr '*' ' ')
+    [[ "${EXPECTED_RESPONSE}" = "${output}" && "$status" -eq 0 ]]
+}
+
+@test "Get Unreleased FBC related images: valid-fbc-fragment-isolated and index with tag" {
+    run get_unreleased_fbc_related_images -i valid-fbc-fragment-isolated -b registry.redhat.io/redhat/redhat-operator-index:v4.15@randomsha256
+    EXPECTED_RESPONSE=$(echo "[ **\"registry.redhat.io/foo/bar@sha256:my-bar-sha\" ]" | tr ' ' '\n' | tr '*' ' ')
+    [[ "${EXPECTED_RESPONSE}" = "${output}" && "$status" -eq 0 ]]
+}
+
+@test "Get Unreleased FBC related images: valid-fbc-fragment-isolated and custom index" {
+    run get_unreleased_fbc_related_images -i valid-fbc-fragment-isolated -b registry.io/random-index:v4.20
+    EXPECTED_RESPONSE="[]"
+    [[ "${EXPECTED_RESPONSE}" = "${output}" && "$status" -eq 0 ]]
+}
+
 @test "Get Image Labels: valid-image-manifest-url-2" {
     run get_image_labels valid-image-manifest-url-2
     EXPECTED_RESPONSE="architecture=arm64"