Bus operators fear a 66 per cent rise in parking fees at Oxford's park-and-rides may lead to chronic congestion in the city.

In an attempt to generate an extra £100,000, Oxford City Council plans to increase charges from 60p to £1 and scrap discounted tickets.

The council has been criticised over the plans for Redbridge, Seacourt and Pear Tree, because the county council continues to charge nothing at its Thornhill and Water Eaton sites.

The Oxford Bus Company has written to the city council expressing concern, while Stagecoach said it was rare for an authority to charge for park-and-ride parking.

Philip Kirk, the managing director of the Oxford Bus Company, said: "When we first heard the city council was planning to increase parking charges at their three park-and-ride car parks, we asked them to reconsider.

"In the past year, the number of people using the park-and-ride bus services has risen by six per cent and those are likely to be people who would otherwise have used their cars to travel into the city centre.

"We have deliberately frozen our ticket prices to encourage more people to use the scheme.

"The increase obviously widens the gap with the two county council-owned car parks at Thornhill and Water Eaton, where there's no charge for parking."

From May, city centre car parking charges are to rise by 25 per cent on Saturdays, with inflation-matching increases at all other times.

While Seacourt and Pear Tree are close to capacity during the week, Redbridge is often only two thirds full. Thornhill is usually full during the week, but Water Eaton is barely half full.

Liberal Democrat city councillor Jean Fooks said: "I very much regret this. We have had a letter from the bus companies saying the last thing we should be doing is increasing parking charges at park-and-ride sites. I don't think it's sending the right message and anything that contributes to fewer people using park-and-ride is a bad idea.

"If people don't use park-and-ride, they could end up driving into the city - and that's bad for air quality."

Stagecoach spokesman Chris Child said: "In most cities and towns there is only one charge - and that is normally taken on the bus.

It's better to have free park-and-ride, as a rule."

The decision to increase the fees was taken after a long debate. Green group leader Craig Simmons said: "I'm not sure it's going to make a lot of difference.

"The (Oxford Bus Company) has progressively increased ticket prices from the park-and-ride and that's a far greater part of the cost. This wasn't one of our policy ideas, but one we reluctantly accepted."