Workers at Peru's biggest copper and zinc mine, Antamina, will start a new indefinite strike on Wednesday to continue pushing for a bonus and other benefits, union leader Jorge Juarez said.
The union ended a 19-day strike on Nov. 30 after Peru's work authority declared it illegal. The mine said the stoppage did not affect production that had been running at around 30,000 tonnes per month.
BHP Billiton and Glencore Xstrata each have 33.75 percent stakes in Antamina. Teck Resources holds 22.5 percent and Mitsubishi Corp 10 percent.
"We are going to start the strike at 00:00 Wednesday (0500 GMT) for the same reasons as the previous strike," said Juarez, the secretary general of the SUTRACOMASA union.
Unionized workers hoped to secure a bonus to offset shrinking proceeds from a revenue-sharing agreement and other benefits as production slips on lower ore grades.
Antamina urged the union to reconsider staging another stoppage.
"The strike it led nearly two weeks ago only hurt the workers, whose salaries had to be reduced as a result of the action," the company said in an emailed statement.
Antamina has said it will probably produce about 336,000 tonnes of the red metal this year, down 27 percent from 2013.
Antamina, in the Peruvian highlands region Ancash, produces about 30 percent of Peru's copper and 20 percent of its zinc. Peru is the world's third largest copper producer.