A controversial copper mine divided Panama. Now voters will decide.

Panama will hold a referendum to decide whether to scrap a copper mining contract in a biodiverse region, following days of protests by thousands of people opposed to the open pit project.

The vote will take place Dec. 17 and its result would be binding, President Laurentino Cortizo said in a video message, according to Reuters.

“I’ve respectfully listened to those who oppose the contract with Minera Panama,” Mr. Cortizo said, using the local name of Canadian mining company First Quantum.

Neither First Quantum nor Minera Panama immediately responded to requests for comment, according to Reuters.

Protesters blocked streets across Panama last week. Teaching and construction unions led calls against the contract with environmentalists, saying continued development threatens forested land and crucial groundwater just 120 kilometers (75 miles) west of the capital, in the state of Colon.

Across Panama City, peaceful protesters handed out fliers, but in some areas on the outskirts of the capital police met protesters with tear gas. In anticipation of the largest marches since a cost of living crisis last July, both the Department of Education and the University of Panama cancelled classes last week.

The government used social media to highlight the “enormous contribution” the mine – Panama’s largest private investment ever – makes to the country’s economy.

In March, Panama’s legislature reached an agreement with First Quantum, allowing its local subsidiary, Minera Panama, to continue operating a huge open-pit copper mine in central Panama for at least 20 more years. The mine was temporarily closed last year when talks between the government and First Quantum broke down over payments the government wanted to receive.

Protests began after Mr. Cortizo signed off on that contract earlier this month, after it was approved by the congress.

The president acted surreptitiously, according to Fernando Abrego, leader of Panama’s Association of Teachers union. “The government decided this confrontation by quickly and expeditiously approving a contract they know is rejected by the people,” he said.

In a statement late Sunday, Mr. Cortizo’s office noted that the contract was first established in 1991, according to Reuters.

Teachers were joined by construction workers, who are one of country’s most powerful labor groups. “The people are in the streets in defense of sovereignty,” said union leader Saúl Méndez, “in the face of a contract that cedes self-determination by devastating the environment to steal resources.”

It is unclear how persuasive these arguments will prove against the economic boon of a single mining site that already brings in 3% of the nation’s gross domestic product. Minera Panama says the mine will employ thousands of Panamanians and that its shipments make 80% of the country’s total exports.

The Cobre Panama mine’s activity accounts for nearly 5% of the country’s economy, and last year represented about half of First Quantum’s EBITDA, according to Reuters.

On Saturday, Minera Panama voiced concern after protesters on boats approached the international Punta Rincon port where it operates, Reuters reported.

“We are deeply concerned by this incident, which represents a significant threat for our operations and the safety of our workers,” it said in a statement, calling the actions “illegal and violent.”

The new contract, initially slowed by labor disagreements, secures Panama at least $375 million a year from Minera Panama, over 10 times more than the previous deal. It represents one of the largest national mining contracts in a region where other countries like Costa Rica regulate the sector more stringently and El Salvador which banned metal mining in 2017.

For teachers, however, Mr. Abrego said concession was not an option. “We will remain in the streets,” he said last week.

After Mr. Cortizo’s announcement, Panama’s main workers’ union said its members will keep protesting in the streets until the contract is annulled, according to Reuters.

“There’s no maneuver in this fight that will deceive the people,” a union representative said.

This story was reported by The Associated Press. Material from Reuters was used in this report.