Some Panamanian members of congress will visit First Quantum's copper mine next week, as a vote looms on a contract which would guarantee the Central American government annual income of $375-million, a lawmaker said on Wednesday.

The contract is a hot issue in Panama where opponents object to its environmental impact and permits to broaden operations.

Juan Diego Vasquez, a member of the congressional trade commission holding consultations on the contract, told Reuters the visit is scheduled for Tuesday, adding he is aiming to change it to another day so more officials can attend.

Authorities from the government of President Laurentino Cortizo have said they will take any findings from the visit into account to clear any doubts about the contract among lawmakers and the population and mull appropriate changes.

"I am going to wait for the commission to finish that process and then we will evaluate... We have always been willing to listen and improve (the contract) to the extent that it can be improved, but at this moment I would not want to get ahead," Trade Minister Federico Alfaro Boyd told reporters on Tuesday.

Cortizo's administration and the Canadian miner agreed on the final text for a contract to operate the key Cobre Panama copper mine in March.

Boyd told Reuters at the time he was confident the text would get the green light from authorities. First Quantum did not immediately reply to a request for comment on the contract's future.

Panama is set to hold general elections next year. Most presidential candidates have come out in favor of the contract, but the reception has been mixed among lawmakers.

Hundreds of demonstrators gathered near Panama's presidency to protest the contract on Wednesday, demanding more environmental protection and fewer expansion permits.

Authorities said in March the country would receive about 10 times more money with the new contract than what it was getting under the previous deal.

First Quantum paid $57 million in royalties during 2022, from Cobre Panama's $3 billion sales revenue, according to company data.