By Nathan Gill

Oct. 5 (Bloomberg) — Workers at the Andina unit of Chile’s Codelco, the world’s largest copper producer, voted to reject a preliminary wage offer from the company, a union leader said.

About 70 percent of the 1,140 unionized workers in a Sept. 30 vote rejected the offer for a 3 percent pay increase plus an attendance-based bonus, Cristian Munoz, treasurer of the Andina union, said in a telephone interview today. Company and union representatives will resume negotiations Oct. 15, Munoz said.

Codelco is investing $11 billion to revamp aging mines and boost output after strikes and other interruptions curbed production in 2008. Andina, located 80 kilometers (50 miles) north of Santiago, produces about 218,000 metric tons of copper a year and about 2,500 tons of molybdenum, according to the company’s Web site.

Codelco doesn’t comment on salary negotiations, said a spokeswoman who can’t be named because of company policy.