Chile's Collahuasi workers say won't back down in mining dispute

(Adds comment from company)

SANTIAGO, June 23 (Reuters) - Workers at Chile's massive Collahuasi copper mine on Tuesday said they would not back down in a conflict with employers and urged miners elsewhere to stage a national strike.

The principal union at the Collahuasi mine, owned jointly by Glencore Plc (Xetra: A1JAGV - news) and Anglo American Plc (LSE: AAL.L - news) , described the firing of 31 striking workers eight days ago as "disproportionate," and vowed to continue agitating until an agreement was reached.

The company said the 24-hour strike on June 15, which workers used to demand better working conditions, was an illegal breach of the collective labor contract that is valid until 2017.

"We are keeping our stance of using dialogue to resolve differences with workers...we are not going to accept illegal mechanisms of applying pressure," it said in a statement on Tuesday.

Among the union's demands are improved transport and more generous lunch schedules, roughly in line with concessions supervisors reached with employers in recent negotiations.

"We will not quit, and we will continue to mobilize until a final agreement is reached," the union said in a statement.

The union urged "miners that are staff and contractors, at private and state-owned companies, to mobilize and move towards a national mining strike."

The union has received the support of the Mining Federation, a union umbrella organization in the top copper exporter.

The Collahuasi mine, located in northern Chile, employs over 2,500 workers. Last year, the mine produced 470,400 tonnes of copper, or 8 percent of Chile's total output. (Reporting by Fabian Camero; Writing by Gram Slattery; Editing by Gary Crosse and Andrew Hay)