MEXICO CITY, Aug 12 (Reuters) - One man was killed in a battle between hundreds of miners at a Mexican copper mine close to the U.S. border, the government said on Sunday, the latest violence in a long-running labor conflict.

About 250 miners from two groups fought close to the La Caridad mine in the northern state of Sonora on Saturday night, state Secretary for the Interior Roberto Ruibal told Reuters.

"There was a battle between two groups, one group who work at the mine and another group of former workers," Ruibal said. "One person died," he said.

Ruibal said it was not clear how the unidentified man died, but he denied union claims the man was shot. He said police arrested six people.

Mexico's mine workers are engaged in a power struggle within the miners union and with La Caridad owner Grupo Mexico <GMEXICOB.MX>.

The Mexican mining industry has been hit by numerous strikes since last year by workers loyal to union boss Napoleon Gomez, who is accused of corruption by other workers and Grupo Mexico.

Three steel workers were shot dead in April 2006 when police used firearms to try and break a strike at the Lazaro Cardenas steel mill in western Mexico.

La Caridad produced about 70,000 tonnes of copper last year until it was closed for months by a strike that only ended when Grupo Mexico fired all the workers.

Most were rehired under a new contract, but about 80 were not, Ruibal said.

Grupo Mexico and the union gave conflicting versions of what caused Saturday's violence, but it appears some of the fired men wanted to enter the mine and were turned back by a large group of workers.

The union said the man killed was one of the former workers and loyal to Gomez. Spokeswoman Carmen Romero said the men had won a court ruling ordering the company to reinstate them.

A strike at La Caridad's larger sister mine Cananea has crippled production there since July 30. A court decision on legality of the strike is due next week.

AlertNet news is provided by