Big business is still polluting the environment despite larger fines and more prosecutions, according to a new Environment Agency report.

Naming and shaming the worst offenders, the report identifies seven large companies which have refused to reform their practices.

In its fifth annual report the pollution watchdog claims that contamination crimes need a much higher priority if punishments are to have an effect.

The "spotlight on business environmental performance survey" documented the best and worst behaviour by firms in England and Wales in 2002.

Water and electricity supplier United Utilities received the most damning report having been fined £327,500 for its sins.

Anglian Water and Thames Water did little to improve their industry's reputation, coming second and third on the repeat offenders list with fines of £285,000 and £135,000 respectively.

BP is fourth on the list with a fine of £60,000.

Many of the biggest fines were given to UK stock market listed companies who claim to be leaders in corporate social responsibility.

The Environment Agency said the pollution caused by these companies despoiled the environment for local communities and some pollutants put wildlife and human health at risk.

They added that the findings undermined a 21 per cent cut in serious pollution incidents caused by businesses, as well as significant reductions in emissions of key pollutants.

The Agency's chief executive Baroness Young of Old Scone said the maximum fines that can be levied at present were insufficient for multi-million pound firms.

"Courts are getting tougher on environmental offenders but fines are still small change for big business," she said.

"The Environment Agency is leading the world in developing new and inventive ways to help encourage environmentally-sound behaviour by big business.

"We have introduced risk-based charging, linking licence fees to environmental performance.

"We assess the risks of an industrial site and the company's management and control of those risks.

But she added that the naming and shaming approach was working.

"The good guys are recognised for their hard work while the poor performers are penalised through the publication of their prosecution records as well as higher operating charges," she insisted. "Signs suggest that it's starting to work."