A ship with supplies for Canadian miner First Quantum's unit in Panama was unable to dock as local boats blocked off access to the key port, the company said in a statement to Reuters on Friday.
Protests have escalated in recent weeks against the miner's contract for a major copper mine operated by the company's local unit, known as Minera Panama.
The ship in question has remained in Panamanian waters for several days without being able to reach the Punta Rincon port due to protests, but on Thursday the captain was forced to call the authorities because the ship needed to dock urgently, the company said.
"The illegal actions carried out by small vessels in the port of Punta Rincon have affected the delivery of supplies that are required by Minera Panama, including for energy generation," the company said.
The company said "the ship fully complies with all international safety regulations and its crew is safe."
Panama's National Aeronaval Service (Senan) has identified the ship as the coal-carrying "CSL Tarantau."
On Thursday, the ship attempted an emergency docking, but the captain aborted the attempt to avoid an accident, Senan said, without providing details on the emergency.
Earlier this week, First Quantum reported that the protests blocking the port had reduced ore processing at its Cobre Panama mine, the first sign that the mine's output was at risk.
On Thursday, the union for Minera Panama said it reached agreements with the company to ensure worker pay as protests kept some workers from reaching their jobs.
The protests began after the Panamanian government and First Quantum signed a new contract on October 20 for Cobre Panama, which contributes 1% to global copper production and 5% to Panama's gross domestic product.
The demonstrators say the new terms are too generous to First Quantum and allege corrupt practices in its approval. The company has denied the allegations.
(Reuters - Reporting by Eli Moreno; Writing by Brendan O'Boyle; Editing by Kylie Madry)