Owner UK Coal had announced before Christmas it planned to spend �18m on Welbeck Colliery, near Ollerton, to access new reserves.

But the discovery of a geological fault means the company has had to go back to the government to submit a new mining plan.

The colliery employs 450 people and a spokesman for UK Coal said the company was confident it would overcome the problem.

The company has put two other pits under review - Rossington near Doncaster and Ellington in Northumberland.