Escondida, a giant mine complex in the Atacama desert in northern Chile, produces about five percent of global copper output, some 927,000 metric tons (one million tons) a year.
Three-month copper on the London Metal Exchange climbed 1.3 percent to $5,869 a tonne by 0054 GMT, erasing 0.9 percent losses from the previous session.
BHP Billiton said on Tuesday it would halt production during the strike because it could not guarantee the safety of the 80 workers the government had authorized to remain at the mine to perform "critical duties", such as equipment upkeep and adherence to environmental protocols.
Fearing a strike at the Escondida mine and expectations that it could trigger supply disruptions at other mines as well, prices for the red metal have been trading at an nearly 18-month high of $6,000 a tonne.
Freeport had warned last week it could be forced to cut staff and production at Grasberg if it did not get a new export permit by mid-February. "We are looking for $3 a pound ($6,614 a tonne) for this year".
Concentrate exports from the mine in Papua, Indonesia, were halted on January 12 as part of Indonesia's push to add value domestically to natural resources.
The union said late Thursday night that the company had asked for mediation by Chile's Labor Directorate which effectively extends negotiations and pushes back the start of a possible strike, the report said. Shanghai Futures Exchange copper rose 1.3 percent to 47,390 yuan a tonne.