The council was fined £18,000 at Darlington Magistrates Court. It was also ordered to pay £7,722 costs.

The case came after a HSE investigation followed a complaint in January 2006 by a maintenance worker, who discovered that the plant room of the council-run leisure centre where he had worked for many years contained asbestos.

HM Inspector of Health and Safety, Richard Bishop, said: "A survey had been carried out in 2001 which identified asbestos containing materials. This information was not acted upon and no-one who worked in the plant room was made aware. As a result, work that was liable to disturb the asbestos was done without the necessary precautions required by law to protect their health from exposure.

"This case should serve as a warning, not only to Local Authorities, but to everyone responsible for carrying out or contracting maintenance work on buildings where asbestos may be present.

"With up to 4,000 deaths per year - that's around 15 times the current rate of fatal accidents at work - asbestos-related diseases are the largest occupational killers in the UK. There is still a legacy of asbestos in buildings that needs addressing. It is estimated that some half a million non-domestic premises contain asbestos of some type. And this means there are still workers putting themselves at risk every day. Recent studies estimate that a quarter of those dying from an asbestos-related disease worked as electricians, plumbers, maintenance workers or builders."