Panama will hold a referendum on whether to revoke the controversial contract awarded to Canadian copper miner First Quantum Minerals, as the government tries to calm mass unrest triggered by the deal.

The vote will be held on December 17, President Laurentino Cortizo said Sunday in a national address. On Friday, Cortizo signed a decree banning all new metal mining contracts.

The revised copper mining contract with First Quantum was approved in congress on October 20 and signed into law by Cortizo. Protesters blocked highways and clashed with police last week, with one of their demands being a referendum.

The Supreme Court has also said it will consider two lawsuits filed against the renewed contract with the company.

Many Panamanians say the revised operating contract is overly generous to the Canadian miner, and violates the nation’s sovereignty over its mineral resources. The contract gives First Quantum the right to produce copper at its site for 20 years, with the option to extend that for a further 20 years after that.

The mine is First Quantum’s top money-maker and accounts for about 1.5% of global copper output.

The company didn’t immediately reply to a request for comment sent outside normal business hours.