U.S. President Joe Biden"s administration on Tuesday said it would suspend oil and gas leases that had been handed out in an Alaska wildlife refuge during the final days of the Trump administration pending an environmental review. The action reverses one of former President Donald Trump"s signature efforts to expand fossil fuel development in the United States, and delivers a setback to the Alaskan state government which had hoped opening the enormous refuge would help revive its declining oil industry. Trump"s Interior Department sold the leases in the Arctic National Wildlife Refuge (ANWR) in January over the objections of environmentalists and indigenous groups. "President Biden believes America"s national treasures are cultural and economic cornerstones of our country and he is grateful for the prompt action by the Department of the Interior to suspend all leasing pending a review of decisions made in the last administration"s final days that could have changed the character of this special place forever," White House National Climate Advisor Gina McCarthy said in a statement. Biden"s Interior Department said it had notified the leaseholders, which include an Alaska state agency. The review, which will examine "legal deficiencies" in the previous administration"s environmental analysis of leasing in ANWR, will determine whether the leases would stand, be voided, or be subject to mitigation measures, the statement said. During his campaign, Biden had pledged to protect the 19.6 million-acre habitat for polar bears, caribou and migratory birds. He also promised to end all new oil and gas leasing on U.S. federal lands, source of a quarter of the nation"s petroleum. The ANWR leasing program is already the subject of lawsuits by environmental and indigenous groups that allege the Trump administration violated federal law by performing a faulty environmental analysis that failed to adequately consider its impact on wildlife and native people. Columbia Law School professor Michael Gerrard called the move "prudent" given the questions around whether the leases were lawfully granted, but said the matter may just end up in court. "At the end of this review, they will make a final decision, and whoever is unhappy with that decision at that time may decide to institute litigation," Gerrard said. Alaska-based green and indigenous groups that sued to stop the lease sale cheered the move. "We look forward to working with the administration on stronger action to correct this unlawful leasing program and preserve one of our nation"s most majestic public lands," groups including Alaska Wilderness League and the Gwich"in Steering Committee said in a joint statement. The first sale of tracts in the refuge, held two weeks before Trump left office in January, received limited interest from the oil and gas industry and generated high bids of just $14.4 million. An Alaska state agency won nine tracts at the sale, while small independent companies won two. The leaseholders, the Alaska Industrial Development and Export Authority, Knik Arm Services LLC and Regenerate Alaska Inc, were not immediately available for comment. Leases were ultimately issued for nine tracts covering 430,000 acres (1,740 square kilometers), Interior said.