Car addicts will be able to seek help for their 'habit' at Oxford's annual Car Free Day on Friday.

As its name suggests, the event, organised by Oxford City Council, aims to get as many people who work in the city to leave their cars at home for the day.

But this year a 'petrol addiction rehabilitation clinic' will be the highlight, offering 'addicts' prescriptions in the form of information about alternative forms of transport in and out of Oxford which, enviromentalists claim, is one of the most polluted cities in the UK.

Last year, an estimated 700 people took part in the city's Car Free Day.

One civic leader who is not expected to attend the celebrations is Oxfordshire County Council leader Keith Mitchell, who earlier this year dismissed Oxford Car Free Day as "silly tokenism".

Mr Mitchell, who lives near Adderbury, 23 miles north of Oxford, told the Oxford Mail it would be too inconvenient to leave his BMW Z3 at home and use public transport to travel to and from County Hall.

Mr Mitchell was unavailable for comment.

However, Oxford Lord Mayor Jim Campbell is expected to be at the event, which is being held in Broad Street.

City councillor Jean Fooks, executive member for a cleaner city, said: "Car Free Day is a fun event but it has a serious message.

"Oxford suffers from bad traffic congestion and this can have a bad effect on people's health, but it also affects people's ability to get around the city.

"We hope car free day will make people think about how they travel in the city."

The event runs from 9am-5pm.

Stalls will include contributions from Oxford cycling pressure group Cyclox, the Pedestrians' Association, Aspires Fitness and the Forest of Oxford.

There will also be the opportunity to visit the surgery of a bike doctor for a free bike safety check.

Entertainment comes in the form of music from the Oxford Improvisers, poetry from the Backroom Poets and Morris dancing.

Meanwhile, Oxford Bus Company will be running competitions to win free bus travel and Stagecoach will sell its weekly Megarider ticket at half price on the day.

Highfield Residents' Association at Headington is planning its own Car Free Day celebrations with a street procession along All Saints Road, which will be closed from Lime Walk to Bickerton Road to all traffic between 3pm and 6.30pm.

A city council spokesman said: "The aims of Car Free Day are to encourage the use of alternative forms of transport instead of private cars, to raise awareness among the public of the risks connected with pollution, and to show how towns and cities could look with much less traffic."