The Durham-based producer bought the deep mine from UK Coal for £21.5 million in 2007.

Work at the mine dates back to 1907 but recent underperformance and a roof fall in 2006 have begun to affect the operation’s economic viability.

Current development work at Maltby has been complicated by an increasing ingress of water, oil, gas and other hydrocarbons where the miner is outfitting a longwall tailgate section.

Hargreaves production division director Gerry Huitson said the unusual geological conditions had created a unique challenge.

“This is a very unusual situation and to our knowledge this has never happened before in Maltby’s long 100-year history,” he said.

“No one on the mining team, including our independent expert geologist with 32 years’ experience at many different UK mines, has come across these conditions before.

“We will revise the mining plans to avoid this locality and it is highly unlikely that these conditions will be found again in any subsequent panels.”

The company said production delays of 12 to 16 weeks could be necessary to ensure safe operations and while this year’s profits will be unaffected, numbers for 2013 could be down significantly.

“Whilst we are bitterly disappointed by this development, health and safety concerns far outweigh those of operational or financial performance,” Hargreaves chief executive Gordon Banham said.

“I am confident that this was the right decision and also that there was nothing that could have been done by the mining team to foresee or avoid this situation.

“With the support and help of the staff and unions, the face gap should not reflect on the longer term viability or profitability of the mine and we will work hard to mitigate the resulting impacts.”