ANCHORAGE — A national environmental group is asking federal fisheries officials to block a drilling company’s plans for offshore hydraulic fracturing in Alaska’s Cook Inlet.

The Center for Biological Diversity says fracking by BlueCrest Energy will threaten endangered beluga whales.

The group says no hydraulic fracturing by the Fort Worth, Texas-based company should be allowed unless there’s additional environmental review.

Hydraulic fracturing is the extraction of oil and gas from rock through injection of high-pressure mixtures of water, sand and chemicals.

Center for Biological Diversity attorney Kristen Monsell says fracking increases risks of spills, earthquakes and toxic pollutants to belugas.

Benjamin Johnson, chief executive officer of Fort Worth-based BlueCrest Energy says he doesn’t even consider the company’s plans to be offshore drilling.

Johnson says the company will drill about four miles horizontally from a well on shore to reach oil deposits.

He says drilling 7,000 feet below the ocean bottom presents no danger to belugas from chemical leaks, noise or earthquakes.

Johnson responded to a letter sent Wednesday by the Center for Biological Diversity to the National Marine Fisheries Service.

The environmental group wants the agency to block BlueCrest’s plans for fracking, the extraction of oil from rock through injection of high-pressure mixtures of water, sand and chemicals.

National Marine Fisheries Service spokeswoman Julie Speegle says the letter has not been reviewed.