More than 100 000 metric tons of copper concentrate stuck at the closed First Quantum mine in Panama do not currently pose an environmental risk, Panamanian President Jose Raul Mulino said on Thursday.

The mine, one of the world's top sources of copper, was shut down in November after Panama's Supreme Court declared Canadian First Quantum's contract with the country unconstitutional, a move that followed environmental protests.

Since then, commodities markets have been watching to see what decision Panama's government takes on whether it will allow the export of the 130 000 tons of copper concentrate left behind after the mine's closure.

Mulino said environmental authorities visited the site a little over a month ago and concluded that the stocked copper was environmentally safe for the moment. Environmentalists as well as mining companies had raised concerns over risks from leaving the copper on site.

"I asked Minister (Juan Carlos) Navarro to conduct that investigation, and he says there is no environmental threat right now," Mulino said at his weekly press conference.

He added that the government plans to decide in January whether First Quantum's proposed maintenance plan for the mine, known as Cobre Panama, can move forward.

First Quantum declined to comment. The company in a statement in April called for immediate removal of the copper concentrate to mitigate potential problems.

"Due to prolonged storage pending export authorization, increased drying and chemical reactions that produce hazardous gases and elevated temperatures are being observed in monitoring, posing significant health, safety and environmental risks," the company said in the April statement.

A plan for removing the copper must address payment for the metal, as well as an ongoing protest against the mine by fishing boats that are blocking the mine's pier, Mulino said.

"If it has to be taken out, it has to be taken out, but there also has to be payment to us, Panama, because it is our material extracted under a concession that no longer exists," Mulino said.

"All those things will eventually be part of the comprehensive review of the problem," he said.

Cobre Panama, when operational, accounted for 40% of First Quantum's revenue and nearly 5% of Panama's GDP.