ASTANA, Dec 12 (Reuters) - A sit-in by miners of ArcelorMittal's Kazakh unit widened to all of the firm's coal mines on Tuesday, the company said, as hundreds of workers demanded a 100 percent wage rise.
ArcelorMittal Temirtau, the Central Asian nation's biggest steel mill, said it was in talks with the miners. It did not say how the strike could affect its output.
"The work of (the) grievance committee is in progress," the company said in a statement.
The protest started on Monday when miners refused to leave four of the company's eight mines. On Tuesday, the firm said all eight mines had stopped producing coal.
Kazakh news website Zakon.kz quoted Labour Minister Tamara Duisenova as saying on Tuesday that 684 workers were on strike and were demanding a 100 percent wage increase. Duisenova said the miners were being paid between 208,000 tenge (about $620) and 326,000 tenge (about $970) per month.
The company, which produced about 4 million tonnes of steel last year, said in September it was negotiating a new collective agreement with steelworker and miner trade unions and planned to sign it before the end of the year.
Large-scale industrial action is rare in Kazakhstan whose government, according to international human rights groups, has cracked down on independent trade unions.
Strikes and protests by oil workers in the Kazakh town of Zhanaozen in 2011 culminated in clashes with police and the death of at least 15 people. (Reporting by Raushan Nurshayeva; writing by Olzhas Auyezov; Editing by Adrian Croft)