LIMA, Nov 27 (Reuters) - The union at Peru's largest copper and zinc mine told Reuters it would call off a strike at Antamina by Sunday, but said it was already planning a new walkout in December.
The labor stoppage at the Antamina mine, which produces about 30 percent of Peru's copper and 20 percent of its zinc, began on Nov. 10, but Peru's work authority declared it illegal.
"We are waiting for the reply to an appeal we made to the authority in order to decide when to return to work," Jorge Juarez, the SUTRACOMASA secretary general said on Thursday. "In any case, it will be at the latest by Sunday."
An Antamina spokesman said the company hoped for things to return to normal next week and to end its contingency plan for preventing the strike from affecting output. SUTRACOMASA says the walkout drastically reduced production, which the company denies.
Unionized workers are demanding a bonus to offset shrinking proceeds from a revenue-sharing agreement. Profit at Antamina has been hit this year by falling production and weak global metal prices.
The union will inform authorities and the mine next week of a new indefinite strike it is planning for Dec. 10, Juarez said.
BHP Billiton and Glencore Xstrata each have 33.75 percent stakes in Antamina, which is also Peru's biggest producer of zinc. Teck Resources holds 22.5 percent and Mitsubishi Corp 10 percent.
Peru is the world's third biggest copper producer and the metal is a leading source of hard currency. Slipping copper output this year from Antamina has added pressure as the country's economy expands at its slowest pace in five years.
In the first nine months of 2014, Antamina's copper production slipped 16 percent to 273,411 tonnes, while its zinc output fell 20 percent to 194,233 tonnes.
Reporting by Marco Aquino; Writing by Sarah Marsh; Editing by Peter Cooney