Liberal Democrat city councillor Jean Fooks has demanded action so that bus drivers who leave their engines running can be fined.

In February, the council's environment scrutiny committee agreed that the authority should adopt the necessary legislation so that drivers could be handed fines, and bus companies agreed to support the move.

But at yesterday's executive board, Mrs Fooks said she was disappointed that Mary Clarkson, executive member for environment, had not done more to pursue the plan designed to cut air pollution, a major problem in Oxford.

Mrs Fooks said after the meeting: "The legal team has found out which bit of legislation we need to use but no business unit has been charged with taking this on.

"If drivers insist on keeping their engines running, even after they have been warned, we need to be able to show them that the council means business."

Ms Clarkson said she would be meeting Tony Payne, the environmental health business unit manager, in the near future to discuss how best to make progress on the fines issue.

She added: "We are trying to do our bit, but bus companies, taxi drivers, and private car owners can do their bit as well by switching their engines off as soon as they possibly can." Under new traffic emission regulations, drivers could be issued with a £20 on-the-spot fine by environmental health officers.

South Oxfordshire District Council adopted the necessary powers in 2002 but has yet to issue a fine.

The level of nitrogen dioxide in Queen Street is almost twice the Government limit, and is also too high in other parts of the city to meet 2005 objectives in the National Air Quality Management Strategy.

Nitrogen dioxide, contained in exhaust fumes, is less harmful than carbon monoxide.

In September last year, the city and county councils formed a joint scrutiny review group to try to tackle the air pollution problem.

City council board members agreed yesterday that the council should continue to compile its Air Quality Action Plan, a series of recommendations on how best to tackle air pollution.

The plan is a requirement of the Environment Act, after Oxford city centre was declared a nitrogen dioxide Air Quality Management Area in September 2001.

Mrs Fooks said the action plan should have been completed and sent to the Government "some time ago".

The board agreed that the effects of the Oxford Transport Strategy would have to be evaluated before the plan could be completed.