Unionized workers at Chilean copper mine Escondida, controlled and operated by BHP Billiton Ltd. (BHP), have accepted an early wage and benefits package, ahead of the Dec. 5 contract expiration date.

The move eliminates the possibility of a strike such as the one that shut down the copper mine, the world's largest, for nearly a month in 2006.

"This is historical; it happened without any conflict whatsoever," said Pedro Marin, the head of the Federation of Mining Workers and a former Escondida union leader.

The 2,250-strong Escondida union belongs to the federation that Marin heads.

In a vote held over the weekend, about 72% of unionized workers accepted the unusually long 44-month contract offer, which included a 5.5% wage increase, bonuses totaling about $25,000, a $6,300 interest-free loan, and various social benefits including an early retirement plan.

The 44-month contract is unprecedented in recent local mining sector negotiations, according to industry participants.

"We are very pleased; the near four-year contract opens new perspectives for labor stability," said BHP Chile spokesman Mauro Valdes.

BHP has a 57.5% stake in Escondida. Anglo-Australian mining company Rio Tinto PLC (RTP) holds 30%, with an additional 10% held by a Japanese consortium led by Mitsubishi Corp. (8058.TO) and the remaining 2.5% by International Finance Corp. (IFC.KW), the private-sector unit of the World Bank.

Last year, the mine produced 1.26 million metric tons of copper, a 15.4% decrease from the 1.48 million tons produced in 2007, as a result of lower ore grades and technical glitches at one of the mills at its Laguna Seca concentrator plant. Escondida produces copper in both cathodes and concentrates. It also produces small amounts of gold and silver.

-By Carolina Pica, Dow Jones Newswires; 56-2-820-4244; carolina.pica@dowjones.com