City councillors are prepared to mount a legal challenge to prevent controversial parking charges being implemented in Oxford.

Oxfordshire County Council wants to charge thousands of car-driving homeowners in the city for the privilege of parking outside their houses in a scheme that could start as early as next year.

Labour county councillor John Sanders, who represents the city ward of Cowley & Littlemore, is among those vehemently opposed to County Hall's plans, which he has called "a fix".

Now Town Hall legal officers are to investigate whether the £40,000 consultation currently under way might have been prejudiced by county council deputy leader and transport chief David Robertson, who said the principle of charging for permits had already been decided.

Earlier this week the city council passed a motion condemning Mr Robertson.

It said: "The 'consultation' being conducted by the county council is biased and has been prejudiced by comments from the relevant cabinet member."

The Town Hall's legal department has been asked to "explore all possible avenues for mounting a legal challenge if the county council proceeds".

County Hall wants to charge residents £40 a year for each of the first two permits issued in most residents' parking zones.

Bedford-based transport consultants Jacobs Babtie are handling the consultation - which lasts until July 20 - on behalf of the county council, which insisted there was no conflict of interest.

The county council has repeatedly come under fire over its transport policy in recent months.

It has made on-street parking free in Oxford in the evenings and on Sundays, benefiting those living outside the city, while continuing a policy on charging those living within the city boundary.

The authority raked in more than £3,000 a day from city centre parking fines between April 2004 and March 2005.

In that period, drivers forked out £1.2m in fines to private company Control Plus, which took over on-street parking enforcement duties in 2003.

A further £1.9m was made from pay display machines, taking the council's total parking revenue to £3.1m.

City council Labour group leader Bob Price said: "Mr Robertson has already indicated that he does not see the consultation influencing the decision on permits there may be changes at the edges, but the principle has been decided.

"The consultation is a waste of money, but it is also potentially unlawful.

"It is a ridiculous questionnaire that does not give people the chance to say what they think."

Questionnaire results are expected to be made public in September.

Mr Robertson added: "If the city feels it wants to spend public money on a legal challenge than I am sure it will take legal advice before taking such a step.

"As I have always said the county council policy is to charge for controlled parking zones. That is a fact of life.

"The consultation is legal and a requirement - we are looking for constructive comments to come back."