By Anthony Esposito and Antonio De la Jara
SANTIAGO, April 9 (Reuters) - Unionized workers at Chilean state miner Codelco began a 24-hour work stoppage early Tuesday at all units of the world's top copper miner to demand greater job security and safety improvements, labor leaders told Reuters.
But workers at private mines, including BHP Billiton (NYSE: BBL - news) , Anglo American (LSE: AAL.L - news) and Antofagasta Minerals , only partially went along with the call for a national strike, even though the union representing them initially said it would join the labor action.
"The strike is under way and it has been a success," said Jaime Graz, union leader at Codelco's giant Chuquicamata mine. "This is a call to attention to the company's management because of the poor security conditions and urgent need for pension and healthcare improvements. It's not just about making more money."
Codelco, which owns about 11 percent of the world's copper reserves, is expected to produce 1.7 million tonnes of copper this year, or just under 5,000 tonnes per day.
Protesting workers delayed the start of the 8 a.m. (1100 GMT) shift by two hours at BHP Billiton's Escondida, the world's largest copper mine, and blocked the access road to Anglo American's Los Bronces mine.
"The workers adhered to the protest, but only for a limited amount of time, a couple of hours. This isn't an action against the company, it's a protest for the problems which at the national level haven't been resolved," said Marcelo Tapia, head of Escondida's union.
Operations "are functioning ... there might be some delay in the start of the shifts, but operations are functioning," Antofagasta Chief Executive Diego Hernandez said.
Workers at the world's No. 3 copper mine, Collahuasi in the Andean nation's copper-rich north, decided not to strike and operations there are normal, a union leader said.
This suggests differences between union leaders prompted private miners to reduce their involvement in the planned strike.
"We're not going to participate in this strike because it's an exploitation of workers' demands ... Collahuasi's operations are normal," Collahuasi union secretary Lincon Espinoza told Reuters.
Collahuasi is owned by Anglo American Plc, Xstrata Plc and a group of Japanese companies led by Mitsui & Co .
Chile is expected to produce 5.58 million tonnes of copper this year.
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