PANAMA CITY - Panama's President on Friday gave final approval of a law authorising a new long-term contract for a major copper mine following lengthy negotiations that will ultimately provide state coffers with much more revenue from the project.

The contract covers operations of a local subsidiary of Canadian miner First Quantum Minerals at the Cobre Panama mine.

The Bill was overwhelmingly approved earlier on Friday by lawmakers in Congress. President Laurentino Cortizo's approval, made official in the government's gazette, was the last step to green-light the contract.

The new contract's terms guarantee a minimum annual income of $375-million to Panama's government, and will be effective for 20 years with the option to renew.

First Quantum paid $61-million in royalties in 2021.

Cortizo's administration and the Canadian miner initially agreed on text for a renewed contract covering the Cobre Panama project in March. But approval then proved elusive, as some legislators demanded changes to some clauses.

An earlier version of the contract was modified to remove clauses such as one allowing the subsidiary to request airspace restrictions, and another that would have extended its remit beyond copper and its associated minerals to also include gold and silver.

Contract negotiations sparked local protests over the mine's environmental and economic impacts. Several streets were closed in the Panamanian capital as hundreds of people demonstrated against the massive open-pit mine.

Felipe Argote, an economist, criticized the contract on social media, claiming First Quantum will take much more from the country economically that it contributes.

Trade and Industry Minister Federico Alfaro said the company's remit is limited to copper and its associated minerals, but no precious metals, in an area of some ​​13 000 hectares.

He said the contract's final approval will send a positive message to future investors.