The 90-year-old Ellington pit in Northumberland is expected to be shut next year.

Its coal is "not of a high enough quality"

Ellington was closed by British Coal in 1994 in the run-up to privatisation, but was bought and reopened two months later by RJB.

At the time of the pit closure in 1994 it was thought Ellington could run for a further five to eight years.

Its workings extend under the North Sea for at least nine miles (15km), but it is thought geological conditions have made it difficult to mine.

RJB explored new reserves at the site in the last 18 months but said the coal found was not of a high enough quality for its customers.

Alcan contract

The company has a further three open-cast mines in the north-east.

It is expected to use these to continue supplying a three-year contract with Alcan aluminium, which has a smelter near the Ellington colliery.

RJB owns a further 13 deep coal mines in England.

It is also reviewing its poorly-performing Stillingfleet colliery in North Yorkshire.

A spokesman refused to give details of the company's plans for the Ellington pit but confirmed: "We have a meeting with the mining unions at Ellington to discuss the future of the mine."