ArcelorMittal Temirtau, the Central Asian nation's biggest steel mill, said it would continue negotiations with the miners.

After hundreds of workers started the sit-in on Monday, the company filed a lawsuit against them and a local court on Thursday ruled the strike was illegal.

State prosecutors then offered miners to end the sit-in in order to avoid charges.

At the same time, ArcelorMittal said it had agreed to increase the pay of those working underground by 30 percent. Miners had demanded a 100 percent rise.

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.

(Reporting by Raushan Nurshayeva; Writing by Olzhas Auyezov; Editing by Michael Perry)