Trade unionists at Severočeské Doly, a brown coal mining company owned by state-controlled utility ČEZ, say workers have gone on strike alert over a pay rise dispute.
A seventh round of collective bargaining held early this week failed to bring an agreement.
The unions are seeking an average pay rise of 2,000 crowns for miners and other workers at Severočeské Doly.
Prague-listed ČEZ has declined to comment on the ongoing negotiations, which began in October.
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