“Regrettably, the board's proposal inevitably means that all employees working at Maltby colliery continue to be at risk of redundancy,” officials said, effectively putting about 500 workers’ jobs on the chopping block.

“In the event that redundancies are necessary, the company remains committed to exploring alternative employment opportunities for staff.”

The company is making good on an August warning that the mine was at risk of closure due to geological conditions.

Officials said geological reports had indicated in recent weeks that the mine’s T125 panel was not viable and that mining at Maltby was risky.

“Although no viable alternative strategic options have been identified by the board at this time, as part of this ongoing consultation process [it] will offer the opportunity to employees and trade union representatives to table alternative proposals,” the company said.

It added that it would continue to make health and safety hazard, geological and financial data available to the trade union.

Hargreaves said that in an effort to conduct a “fair and meaningful consultation”, it would continue to cooperate with union representatives and be open to communication regarding any proposals.

A final decision on the mine’s fate is not far off, as the miner’s board is seeking alternative proposals through November 30.

The Rotherham colliery has been producing coal for more than a century.

The mine, which produces more than 1 million tonnes per annum, supplies about 60% of its output to Europe’s largest coal-fired power plant, Drax Group's North Yorkshire power station.

Much of the remaining production goes to Hargreaves' Monckton works near Barnsley, which uses about 200,000tpa for glass, detergent and steel manufacturing.

The company first disclosed problems at Maltby in May.