Concern is growing over the future of jobs at Unity Mine - one of Wales' largest drift mines.
It follows a day of talks between the NUM and management of the mine in the Neath Valley, where around 200 people work.
The General Secretary for the NUM in South Wales, Wayne Thomas - who attended a meeting with Unity Mine managers this afternoon - said afterwards that there was uncertainty, but there had been no talk of the mine closing.
He added that there is likely to be a statement tomorrow on consultations over possible job losses and the mine's long-term future.
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