Mineral resources at Chile's massive Collahuasi copper mine increased by 40 percent to over 7 billion tonnes, as the deposit seeks to expand output to over one million tonnes per year, operators said on Wednesday.

The mine, which is jointly owned by Anglo American (AAL.L: Quote) and Xstrata (XTA.L: Quote), said mining reserves have increased by 315 million tonnes to 2.453 billion tonnes at a grade of 0.82 percent of copper from an estimate published in December 2009.

Minera Dona Ines de Collahuasi company CEO Jon Evans said in a statement the mine plans to complete expansion studies by the first-quarter of next year.

Collahuasi, which produced 535,853 tonnes of copper in 2009, is one of the world's biggest copper deposits behind Codelco's Norte division and BHP Billiton's (BHP.AX: Quote) (BLT.L: Quote) Escondida mine that produces over 1.25 million tonnes and is also located in Chile.

A strike and protest by temporary workers halted output at the mine for several days in May.

The mine's operator said the new resource estimate comes from new drilling results, modeling changes and metal price assumption adjustments.