Both the union and the company say that so far production hasn't been affected by the walkout, which started Thursday.
The miners went on strike to back demands for higher wages.
"The strike will continue until at least next week," Leonicio Amudio, a union official, said in a telephone interview Friday.
He said that the strike won't start to affect production for a least three or four days.
Late Thursday, a spokesman for Freeport-McMoRan said in an e-mail that, "Production at Cerro Verde has not been affected by the strike."
Cerro Verde's copper production in the first half of 2008 totaled 156,393 metric tons.
Compania de Minas Buenaventura SAA (BVN) and a subsidiary of Sumitomo Corp. (8053.TO) also have equity stakes in the company.
The mine is located in southern Peru.
-By Robert Kozak, Dow Jones Newswires; 511-221-7050; peru@dowjones.com
(END) Dow Jones Newswires
10-03-08 0937ET

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