The Alabama-based miner has reportedly blamed low global coal prices and the threat of a wind farm near the South Wales operation as factors in possible cutbacks.

According to a BBC report, Walter is concerned about the implications of the planned wind farm near the colliery which it said could “sterilize” land for mining.

Walter which acquired the mine in April 2011 sent letters to employees warning of a “threat of redundancies.”

“Whilst Walter Energy remain committed to continuing the project at Aberpergwm colliery, whereby we aim to make a sustainable profitable business creating employment for many years to come, unfortunately we aren’t in a position to continue with the project at the pace that we are at present, and therefore must scale back until circumstances change,” the report quoted from the company statement.

The implications of a local planning application for a wind farm above Aberpergwm were directly referenced in the letter.

“Should this application be accepted, then this may sterilise the land for mining purposes and as such further jeopardise the employment of those at Aberpergwm.”

Walter’s UK operations also include an open cast mine, a coal processing and a coal blending plant.