Conservative groups claim that Mr Biden’s suspension of the leases may be illegal. “The government cannot sign a $ 14 million contract and then void the contract without giving a reason,” said Devin Watkins, an attorney for the Competitive Enterprise Institute, an organization that worked with the Trump administration to take back environmental protection. “No reason was given to terminate the ANWR leases.”

Political experts also noted that any move by Mr Biden to block drilling in the Arctic could be reversed by a future government.

“Since the Carter administration, ANWR rental has been determined by which party sits in the White House,” said Marcella Burke, an energy law attorney who served at the Home Office during the Trump administration. “Developers in ANWR assume that there will be a change of policy between Democratic and Republican governments. But it is not permanent, provided that one day there will be another party in the White House. “

Environmental groups welcomed the move, but called for a permanent ban on drilling in the Arctic.

“Until the leases are terminated, they will remain a threat to one of the wildest places in America,” said Kristen Miller, acting director of the Alaska Wilderness League. “Now we expect the government and Congress to give priority to the legal repeal of the oil leasing mandate and to restore the protection of the coastal plain of the arctic sanctuary.”

The refuge, 19 million acres in the northeastern part of the state, had long been closed to oil and gas development, and Democrats, environmentalists, and some Alaskan groups successfully fought efforts to open it.

But President Donald J. Trump opened part of it, about 1.5 million acres along Prudhoe Bay known as the Coastal Plain, a centerpiece of his efforts to produce more domestic fossil fuels.

In 2017 the Congress incorporated the language into a tax bill that introduces a leasing program to generate revenue for the federal government. But an environmental review required by federal law was only completed last year.