Anglo American blamed a group of contractors and "unidentified people” for the occupation of parts of the mine and the takeover of outbuildings and trucks.

About 100 hooded protesters reportedly entered the mine - Anglo's biggest operation in the country and the world's fifth largest copper mine - in central Chile earlier on Wednesday, seizing installations and setting up barricades.

The company said it had requested police intervention and announced that it would take legal action "to protect the rights and safety of its workers and the property."

"The conditions are not present to guarantee the safety of the workers or operate under the necessary standards," Anglo American said in a statement, adding that it was implementing an evacuation plan for the 1,500 workers at Los Bronces.

The UK-based mining multinational from South Africa has - as have its rivals - faced protests in recent months from trades unions at its mines in Chile, whose copper industry is the world's largest producer of the metal and makes up one fifth of Chile's GDP.

Labor disputes 

Unions - led by the Federation of Contract Workers - at the mine say the dispute stems from a process of outsourcing jobs, noting that two out of three workers is now working on short term contracts, with lower salaries and less job security. This, the union said, pits one group of workers against another as the company seeks to reign in costs as lower global copper prices bite into the company's finances.  

The union representing contractors at Los Bronces is reportedly in talks with Anglo, which says its role is "facilitator” in the negotiations.

In September, over 1,700 Los Bronces workers staged a one-week strike over wages. Unions said the company had offered a one-off bonus of 9 million pesos ($13,600) and an interest-free loan of 3 million pesos ($4,500). Union president Eduardo Rocco has also accused the company of reneging on promises to build a dormitory for the workers.

Workers voted 858 to 508 then in favor of strike action after rejecting Anglo's offer.

Los Bronces, located at high altitude and subject to extreme weather, was taken over by South Africa-based Anglo American - one of the world's largest mining conglomerates - in 1980 and had not had a strike until this year.

Los Bronces, 3,500 meters high up in the Andes 65 km north-east of the capital Santiago, is also one of the few Anglo still has in Chile.

jbh/bw (Reuters, EFE)