Saturday shoppers using Oxford's Westgate car park face a 50 per cent increase in charges next year.

The city council has decided to hit car-driving shoppers in the pocket in a bid to deter weekend gridlock and pollution.

Instead, Town Hall chiefs want them to use the park-and-ride or local bus services.

The Oxford Mail has been told of plans by the authority's ruling Liberal Democrat group to raise parking tariffs by half on Saturdays only.

If agreed, a two-hour stay next year would end up costing £4.50 instead of £3, while a four-hour stay would cost £9 instead of the current £6.

Westgate has been singled out because it is easily the city's most popular car park.

City councillor Jean Fooks, executive member for a cleaner city, said: "Saturday is pretty ghastly, car parks can't cope and it seems to me we should be encouraging people to use public transport.

"It's not a case that we are anti-shopper and I hope people will see the environmental sense - it's not a congestion charge but it's akin to that."

Parking in Oxford has become something of a contentious issue recently.

The county council is currently pushing through a policy of charging city residents for parking cars outside their homes and earlier this year wanted to raise early morning on-street tariffs to more than £4 an hour making them some of the most expensive in the UK.

However, they have made on-street parking free during the evenings and on Sundays and parking at County Hall park-and-ride sites (Thornhill and Water Eaton) costs nothing.

On the other hand, the city council has consistently opposed paid-for permits, but continues to charge people for using park-and-ride sites (Seacourt, Redbridge and Pear Tree).

Meanwhile, charges at the city council's five sites (Westgate, Oxpens, Worcester Street, Gloucester Green and St Clement's) have already increased by 20 per cent in the past year.

City councillor Stephen Tall, executive member for better finances, said: "Saturdays are the busiest days for parking in the Westgate car park.

"On most Saturdays, the car park is full and traffic backs up on to Thames Street.

"A special Saturday tariff - at Westgate only - is proposed at a higher rate than other days.

"We hope this will encourage more use of park-and-ride.

"We will review charges across the city park-and-ride sites to see if we can encourage the public to travel in this more environ- mentally-friendly way."

This week, the Government approved plans by Capital Shopping to revamp the 1970s' Westgate shopping mall at a cost of £330m, part of which would involve demolishing the car park.

Work is scheduled to start in 2008 with the centre open in 2011.

Labour group leader Bob Price said: "We have rejected this proposal in our own draft budget.

"It would be a serious blow to the retail sector in Oxford and way out of line with other shopping centres in the region."

Green group leader Craig Simmons added: "It's dangerous for the Lib Dems to rely on generating additional income from the Westgate car park, which will disappear in a few years time following their decision to hand the site over to Capital Shopping".