* Papers filed for new strike starting next Wednesday
* Cerro Verde says production not affected by strikes
* Workers at Shougang Peru iron mine still on strike
LIMA, Sept 21 (Reuters) - Workers at Peru's Cerro Verde mine, which yields 2 percent of the world's copper, have pushed back the start date for an indefinite strike to next Wednesday from next Tuesday, a union leader said.
The 1,100 workers at Cerro Verde, controlled by Freeport McMoRan (FCX.N), had downed their tools on Sept. 14 but went back to work on Saturday at the mine in southern Peru to avoid the government declaring the strike illegal.
They now have all their paperwork in order to seek higher wages and better benefits by striking indefinitely, union head Leoncio Amudio said on Wednesday.
"We reported the strike deadline to the company and the labor authority yesterday (Tuesday)," Amudio told Reuters. "The new strike will start on Wednesday, September 28 at 7:30 a.m."
Bruce Clements, the general manager of Cerro Verde, told Reuters in an interview last week that copper and molybdenum production had not been affected by the previous strike as the mine had hired temporary workers while it negotiated a new labor contract. [ID:nS1E78E0P8]
Cerro Verde workers want a 5 percent salary raise to 2,000 soles ($732) per month and better benefits. They say the company has offered a 2 percent raise, which they deem unacceptable.
Cerro Verde (CVE.LM) produced 312,336 tonnes of copper in 2010. Freeport McMoRan also faces a month-long strike at its giant Grasberg mine in Indonesia, raising concerns over a global shortage of the red metal.[ID:nL3E7KG0F7]
Mine workers throughout the developing world have downed tools in recent months, demanding a greater share of mining profits at a time metals are fetching high prices on international markets.
Workers at Shougang Hierro Peru, a unit of the Chinese Shougang Group, have been on strike for 22 days and have no plans to return to work. Shougang is currently the only iron producer operating in Peru.
"For us their is no solution to the labor situation," said union leader Julio Ortiz.
Ortiz said the company was not respecting the strike and had hired temporary workers to continue exporting the metal. Shougang, which declared force majeure on Sept. 1, denied claims it had contracted workers.
"That's impossible, we can't contract anyone, the workers are still on strike," said General Manager Raul Vera. "Obviously production at the mine is still halted." (Reporting by Caroline Stauffer and Teresa Cespedes)