(Adds comments from company, union)
SANTIAGO, Jan 11 (Reuters) - Unionized workers at global miner BHP Billiton's Cerro Colorado copper mine in Chile went on strike on Monday after contract negotiations failed, a union official and the company said.
Workers "abandoned the mine, and the strike became effective as of 8 in the morning (1100 GMT)", said union director Gustavo Tapia.
The relatively small Cerro Colorado mine produced 55,600 tonnes of copper from January to September 2015, according to Chilean state copper commission Cochilco.
Workers were "camped out on the road leading to the mine during the first hours of the strike and the production is completely paralyzed," said the union said in a statement.
The union, which represents nearly 700 workers at Cerro Colorado, rejected the company's last proposal of a real wage increase of 1 percent.
"The company deeply regrets the decision of the workers, as the proposal made every effort to reach a mutually beneficial agreement that would ensure the sustainability of Cerro Colorado," BHP Billiton said (Reporting by Fabian Cambero and Anthony Esposito; Writing by Anthony Esposito; Editing by Jeffrey Benkoe)