The firm's chief executive, Tristan Pascall, flew to Panama over Christmas to attend meetings in person, though the sources did not confirm whether he was still there.

Neither the government nor First Quantum, which operates in Panama through its subsidiary Minera Panama, immediately replied to requests from Reuters for comment.

The Panamanian government and the mining firm have been discussing a deal that would have increased annual tax payments to Panama to at least $375 million. In 2021, First Quantum paid $61 million in royalties to Panama based on the output of its flagship Cobre Panama copper, according to the company's annual report.

They are also discussing legal protections over contract duration and terminations.

On Dec. 14, the parties missed the government's deadline to seal the agreement, prompting Panama to order First Quantum to halt operations at the mine. Days later, the firm launched arbitration proceedings against the government.

The mine accounts for roughly 3.5% of Panama's gross domestic product, according to government figures.

The company has invested over $10 billion in the mine, Panama's largest ever private investment, according to the company's web page. In 2021 the mine represented 80% of the country's total exports, Quantum Minerals says.

(Reporting by Valentine Hilaire; Editing by Bradley Perrett)

By Valentine Hilaire