Chile in 2016 gave Albemarle approval to hike production from the lithium-rich Atacama salt flat on condition the miner prove its reserves could sustain the increased output.

But Chilean nuclear agency CCHEN, which also licenses lithium exports, said in January that Albemarle had failed to provide the necessary reserves data, a key stipulation in their permit.

In a letter dated April 22 and addressed to Albemarle, however, CCHEN said it had "thoroughly studied" new reserves data provided by Albemarle and had determined the report was "satisfactory" and complied with the terms of Albemarle's 2016 license.

The rubber stamp brings an end to one of three feuds Albemarle has had in recent months with Chilean authorities, helping to defuse tensions between the U.S.-based lithium giant and the government of the mineral-rich South American nation.

Albemarle's closely-watched expansion in Chile is a key link in satisfying global demand for the electric vehicle battery metal, which is poised to soar in the coming decade as more countries move to electrify transportation.

The company has also entered into international arbitration with another Chilean regulator, Corfo, over royalty payments earlier this year, and has separately filed suit to force the government to turn over a coveted, publicly funded environmental study of the Atacama salt flat.

Albemarle told Reuters by email on Friday that it has "complied with all our obligations and requests from Chilean public agencies."

CCHEN did not immediately respond to a Reuters request for comment.

The spat over reserves data festered for months, in part because Albemarle had initially sought to keep some information confidential, saying U.S. Securities and Exchange Commission rules impeded it from turning it over, filings show.

If Albemarle had refused to budge, CCHEN discussed the "suspension" of the company's permits until it complied with the government's request, according to minutes seen by Reuters from a previously unreported executive committee meeting in which CCHEN discussed the standoff.

CCHEN relies in large part on miners to provide data on the Atacama's reserves. Albemarle is one of two lithium miners operating on the flat, home to nearly one-quarter of the world's current supply of the white metal.

(Reporting by Dave Sherwood; Editing by Rosalba O'Brien)

By Dave Sherwood