(Bloomberg) -- First Quantum Minerals Ltd. said it has been forced to stop processing copper at its giant mine in Panama after the government blocked it from loading the metal at a port in the country.

The move comes amid a dispute between the Canadian company and Panama, which erupted after they failed to reach a tax agreement late last year for the Cobre Panama mine. First Quantum says it’s being forced to halt operations at the flagship facility as a negotiating tactic, while Panama calls it a compliance matter that has nothing to do with negotiations.

Panama’s Ministry of Commerce and Industry said it’s reviewing the company’s certification submission, saying the loading ban is “a technical matter independent of the talks being held for a new contract.”

The mine is First Quantum’s biggest asset, an economic engine for Panama and accounts for about 1.5% of global copper production. The dispute is playing out amid protests in Peru that have disrupted mining, just as Chilean mines suffer a series of operational setbacks. The disruptions underscore the challenge of ramping up supply to meet growing demand for metals crucial to a global shift to cleaner energy.

Shares of the Vancouver-based miner fell 0.9% to C$25.72 at 9:37 a.m. in Toronto.

First Quantum and Panama have been negotiating new tax terms for more than a year. Talks failed to produce an accord by Panama’s Dec. 14 deadline, putting the two sides at an impasse. Negotiations resumed in late December.

• Read more: First Quantum Warns of Copper Mine Disruption in Panama Tax Spat

Panama’s maritime authority ordered port loading to halt over a certification issue earlier this month. This move, which First Quantum said deviated from prior practices, forced the Vancouver-based miner to stockpile semi-processed copper at the mine site. Now it has run out of storage room. The company said it believes all requirements to export have been met.

First Quantum could forgo more than $30 million in earnings before interest, taxes, depreciation and amortization for each week that ore processing is suspended at Cobre Panama, which will pose downsize risk to estimates, according to Bloomberg Intelligence analyst Grant Sporre.

BMO Capital Markets cut its share price target for First Quantum based on a two-week suspension of operations, but remained upbeat that a deal would be done.

“We are optimistic that First Quantum and the government of Panama will reach agreement,” both on the port issue and the broader contract renegotiations, analyst Jackie Przybylowski wrote in a note to clients.

First Quantum said Thursday that it will start a partial demobilization of its 8,000 workers in the country. It said this process would likely accelerate if shipments do not resume in the coming weeks.

--With assistance from James Attwood.

(Adds shares and analyst comment from fifth paragraph.)

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