The federal government said it extended a comment period on proposed regulations for drilling in arctic waters offshore Alaska to allow for more public input.

The Department of Interior has affirmed a 2008 lease sale for exploration in the Chukchi Sea off the coast of Alaska. The decision cleared the way for a formal review of exploration plans in the region, which will include an environmental analysis.

"The original 60-day comment period ends on April 27," offshore regulators said in a Thursday statement. "The 30-day extension will end on May 27 and will allow the public more time to provide input."

Shell devoted about $5 billion and more than eight years of work for its arctic oil exploration off Alaska's coast in the Chukchi and Beaufort seas. The company's drillship Kulluk struck ground off the Alaskan coast in 2012, and the U.S. Coast Guard blamed harsh winter conditions and the company's efforts to escape Alaskan tax laws for the incident.

Kulluk's grounding off the Alaskan coast followed a 2012 exploration season in the arctic waters of Alaska that was complicated by equipment failures.

In 2012, seven Greenpeace activists, including actress Lucy Lawless, were removed from the Noble Discoverer drill ship and arrested by New Zealand authorities. The rig was to leave for the Chukchi Sea off the Alaskan coast to drill exploratory oil wells for Shell.

Activists from Greenpeace occupied another drillship, Polar Pioneer, set for Alaskan waters this month, but were forced to abandon their protest after Shell took legal action against the environmental advocacy group.

Shell said its drilling plan for offshore Alaska is contingent upon the necessary permits and "our own determination that we are prepared to explore safely and responsibly."