UPDATE 1-U.S. no longer 'stable regulatory climate,' miner Antofagasta says

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By Ernest Scheyder

March 31 (Reuters) - The United States is "no longer considered to have a stable regulatory climate," an executive from Antofagasta Plc's Twin Metals subsidiary told a U.S. Senate committee on Thursday after the company's proposed Minnesota copper and nickel mine was blocked earlier this year by President Joe Biden.

The remarks are some of the most-pointed to date by a mining executive against Biden's administration, which miners have said is prioritizing domestic conservation efforts despite saying it wants to boost output of minerals used to build electric vehicles and other products that combat climate change.

Biden's decision to block the proposed Twin Metals was blasted by the mining industry as capricious and not science-based.

Many environmentalists have said Minnesota's Boundary Waters region, where Twin Metals aims to develop its underground mine, is too environmentally sensitive to develop.

Twin Metals has repeatedly complained that it has been at the whim of whoever sits in the White House. Biden's predecessor, Donald Trump, supported the project, but Barack Obama opposed it.

"The United States is no longer considered to have a stable regulatory climate," Julie Padilla, the chief regulatory officer of Twin Metals, told the U.S. Senate's Committee on Energy and Natural Resources.

"The precedent set by these actions shows that a company can ... spend a decade developing a project only to see it be arbitrarily canceled without any environmental review."

Padilla said Twin Metals laid off a third of its workforce last month and halted "millions of dollars in local contractor work" after Biden's decision.

Padilla's testimony comes the same day Biden is expected to invoke a Cold War-era defense law to boost U.S. mining by funding feasibility studies for new mines, though not digging them.

Antofagasta Chief Executive Ivan Arriagada told Reuters earlier this week the company will fight Biden's decision and hopes the mine opens by the end of the decade.

(Reporting by Ernest Scheyder Editing by Chizu Nomiyama)