Nov. 3 (Bloomberg) -- BHP Billiton Ltd., the world’s largest mining company, failed to reach an agreement with striking workers at its Spence copper mine in Chile today, union officials said.

The unions asked Chilean Labor Minister Claudia Serrano to intervene in talks with workers who have been on strike for more than three weeks, Pedro Marin, president of Chile’s Mining Federation, said today in an interview. The conflict is unlikely to be resolved this week, said Marin, who acts as a mediator for almost 5,000 copper workers in Chile.

The Spence strike is reducing global supplies of metal used in power cables and electrical wire, prompting a 5 percent increase in the price of copper traded on the London Metal Exchange last month.

“The company is intransigent in not wanting to offer more benefits to its workers,” Spence union spokesman Andres Ramirez said today in a telephone interview.

Negotiations mediated by the local government in Antofagasta, Chile, for the past two days broke down, he said. No further talks are scheduled, Ramirez said.

BHP London-based spokesman Ruban Yogarajah declined to comment today on the talks in an interview.

December-delivery copper lost 4 cents, or 1.4 percent, to $2.9050 a pound on the New York Mercantile Exchange’s Comex unit at 10:18 a.m. local time. Prices have dropped more than 5 percent from a 13-month high of $3.069 on Oct. 26. Copper for three-month delivery fell 1.9 percent to $6,430 a metric ton on the London Metal Exchange.

To contact the reporter on this story: Matthew Craze in Santiago at mcraze@bloomberg.net.

Last Updated: November 3, 2009 10:31 EST