UPDATE 1-First Quantum CEO: long-term sustainability uncertain if Panama operations end

(Adds background on contract, interview details)

Dec 1 (Reuters) - The chief executive of Canadian miner First Quantum said he would have to look into how the company could sustain its finances in the long term, given Panama's push to annul operations at its local copper mine, the miner's biggest revenue source.

"We have strong finances in the short and medium term, but yes, we have to see how we sustain them in the long term," Tristan Pascall said in an interview with Panamanian newspaper La Prensa published on Friday, when asked about the risk of bankruptcy for the company if Panama operations end.

The company has notified buyers it will not be able to meet agreements due to force majeure, Pascall added.

Panama's top court issued a ruling deeming First Quantum's contract with the government to operate a key copper mine unconstitutional. President Laurentino Cortizo moved to close the mine hours later.

"The court's ruling leaves a lot of questions," Pascall said in the interview, while vowing to keep open dialogue with Panamanian authorities to find solutions for the future of the project.

The Canadian miner said on Friday it has initiated

arbitration against Panama

, with Pascall noting the company still does not know the amount it will be asking from the country during the process. (Reporting by Elida Moreno and Valentine Hilaire; Editing by Brendan O'Boyle)