The company has decided to mothball Harworth Colliery following problems with methane gas and difficult ground conditions in the current developed coal panel, with operations ceasing upon the completion of the current coal face.

The company said Harworth had significant potential further reserves in an alternate coal seam, potential which UK Coal was investigating.

Rossington Colliery’s future is also up in the air unless it finds a way of improving production soon. The mine moved to an advancing mining process following the loss of a developed area of coal in 2002. The company said the advancing face is performing at levels that were insufficient to support further investment in continued coal production.

UK Coal said Welbeck Colliery was performing well following the review process and current output levels had improved to a level that justified further investment in the development of coal reserves. It said output should continue to rise and would improve gain when the next retreat coal face starts production later this year.

Despite the unsure future of some of its mines, UK Coal’s spin remains positive.

“After installing new faces at all deep mines with the exception of Welbeck, UK Coal should enjoy consistent production from its coal faces for much of the second half,” the company said.

“Only Welbeck and Kellingley have scheduled moves in the second half and both relate to coal faces where a significant amount of development has already been done.”