Laurentino Cortizo, who takes office in July, said on Tuesday that the government was entitled to go over the contract "clause by clause."

First Quantum vowed to collaborate with Panamanian officials.

"We will gladly share all relevant documentation related to the extension of the contract," the company said in a statement. "We do this with the conviction that the Cobre Panama project, which employs more than 9,000 Panamanian employees during its current construction phase, can then proceed without any additional legal uncertainty."

The project has attracted $6.3 billion in foreign direct investment, First Quantum said.

The Toronto-based company owns 90 percent of Minera Panama, which was awarded the concession for the Cobre Panama project in 1997. But the country's Supreme Court of Justice declared the underlying law unconstitutional last year.

Cortizo's remarks came days after the national assembly rejected a bill that sought to reaffirm Minera Panama's contract, with legislators arguing that the royalties are too low and the issue should be decided by the incoming government.

(Reporting by Elida Moreno; writing by Julia Love; Editing by Leslie Adler)