Government labor inspectors said Peru's No. 3 copper mine Cerro Verde must stop operating with volunteer workers or pay a fine, according to documents obtained by Reuters and confirmed by the government on Tuesday.
Now in its 13th day, the indefinite strike aiming for higher wages was the first to be declared legal by the government in Cerro Verde's 40-year history.
The mine produced 312,336 tons of copper in 2010 and is controlled by Freeport-McMoRan.
(Reporting by Caroline Stauffer and Marco Aquino)