Contract workers for Chile's state mining company, Codelco, blocked roads into some of the country's largest copper mines to press demands for better pay and working conditions, their union said Tuesday.

The Confederation of Copper Workers said roadblocks went up outside the Chuquicamata mine, the world's largest open pit mine, after the labor action into effect at 5:00 am (0800 GMT).

Similar actions followed at the Division El Salvador, Radomiro Tomic, El Teniente and Andina mines in northern and central Chile, the union said on its website.

The union, which represents about 40,000 workers, also vowed protests at all Codelco mines that have refused to negotiate with workers employed by contractors and subcontractors.

Codelco later issued a statement acknowledging that "takeovers of roads and access at five Codelco divisions, partially affecting... its operations."

The workers, who are pressing for better pay and working conditions, want Codelco to join their negotiations with the mining company's contractors and subcontractors but Codelco has so far declined.

In January, the mining company announced plans to cut spending by $1 billion in 2015 in response to falling copper prices after years of record highs.

Earnings this year were expected to fall to around $2 billion, from $3.03 billion last year.

Chile is the world's biggest copper producer, supplying nearly a third of world demand for the metal.