LIMA, July 5 (Reuters) - Unions at the Peruvian mines of Southern Copper (SCCO.N), Buenaventura (BVN.N), Volcan (VOL_pb.LM) and Shougang (SHP.LM) said they would vote late on Tuesday on plans to hold an emergency strike starting on Wednesday.
Unions want to pressure the government to implement a law passed by Congress that would create a special retirement fund for miners funded by monthly payrolls and corporate profits.
One lawmaker has motioned to block the bill's implementation, frustrating miners who say they will hold a two-day walkout in protest.
But the last two nationwide walkouts called by Peru's national confederation of mining unions have failed and unions were planning to stay at work at the big mines in Peru, including Freeport McMoRan's Cerro Verde (FCX.N) and the Antamina pit of BHP Billiton (BHP.AX) and Xstrata XTA.L.
Workers called off plans for a separate strike days before leftist Ollanta Humala was elected president on June 5. He takes office on July 28. (Reporting by Teresa Cespedes and Patricia Velez; Editing by Marguerita Choy)