It said a decision would be taken early in the new year once results were completed on a new seam at Harworth, Nottinghamshire.

A 45 per cent jump in the market price of coal since the beginning of the year has transformed the outlook for the company’s mining operations.

Its average sale price in the first half of the year was £1.79 per gigajoule, although some coal was sold on the open market at £4 per gigajoule.

UK Coal is Britain’s biggest coal producer, with four deep pits. It reported a half-year loss of £9.9million against a £40.6million profit at the same stage last year.

However, it said, a significant increase in output, as new faces came on stream at higher prices, had put it on course to meet market hopes of annual profits of about £70million.

The company, which bought the rump of the former British Coal, also owns 46,500 acres of land — nearly 4,000 acres of which is tar­geted for development.

UK Coal’s property business delivered profits of £20.5million.