The federal government will consider designating areas in the main Hawaiian Islands as critical habitat for endangered Hawaiian monk seals.

The announcement, to be published in the Federal Register on Friday, comes in a response to a petition filed by three environmental groups.

The petition seeks to expand a protected area now comprising the Northwestern Hawaiian Islands to include the beaches and waters of the main islands.

Environmentalists say monk seals in the main Hawaiian Islands are thriving and giving birth while others are dying of starvation, entanglement in fishing gear, shark predation and disease.

If designated as critical habitat, any federal activities that may affect the habitat must undergo review.