(Adds comment from Freeport)
SANTIAGO, Aug 31 (Reuters) - A Chilean union that represents copper mine workers rejected a move by Freeport-McMoRan Inc to drastically cut staff at its El Abra mine and said on Monday it was considering action.
Last week, Arizona-based Freeport, which owns a 51 percent stake in the mine in northern Chile, became one of the first big global miners to announce it was slashing production because of slumping copper prices.
That would include reducing mining rates at El Abra by about 50 percent to cut and defer costs, and extend the mine's life, the company said.
Over the weekend Freeport began to send out letters announcing the dismissals and refusing to negotiate, said Juana Mejias, who heads the mine's local union, adding that around 700 workers were being fired.
"The situation is complex and a true massacre that they have carried out by dismissing 50 percent of the workforce," she said in a statement on Monday.
However, a spokesman for Freeport said that termination notices had not yet been issued.
"Plans for reductions in the workforce are being developed," he said.
Gustavo Tapia, head of the Chile Mining Federation union, dismissed the fall in the copper price as a "cyclical issue" and said multinational companies had sufficient profits to ride it out.
"In the coming hours we will decide the measures we will adopt as an organization," he said.
El Abra produced around 166,000 tonnes of refined copper last year out of Chile's total 5.7 million, according to figures from state copper commission Cochilco. That placed it just outside the top 10 biggest mines in Chile, which produces about one-third of the world's copper.
El Abra's workforce comprised about 1,600 employees and 1,400 contractors.
Any labor action would be a fresh headache for state-run Codelco, which owns the remaining 49 percent stake in El Abra. Codelco has just resolved a three-week dispute with contractor workers across its operations, which cost some 17,000 tonnes in lost output. (Reporting by Rosalba O'Brien in Santiago, additional reporting by Nicole Mordant in Vancouver; Editing by Richard Chang and Steve Orlofsky)