Traders' claims that Oxford High Street is sinking under the weight of 2,500 buses a day have been described as "irresponsible".

Campaigners battling to reduce the number of buses using the High Street said heavy vehicles could be causing more damage than previously thought.

They believe the historic street could be in danger of sinking unless urgent repairs are made. But Oxfordshire County Council leader Keith Mitchell insisted there was no danger of the road surface subsiding.

He said: "Oxfordshire Highways has completed high-quality work on the previously worn-out sections of the High Street, between Longwall Street and the Plain roundabout and Carfax and Turl Street.

"It plans to tackle the remaining worn-out section during the course of 2009. The whole reason we have been doing work on the High Street and St Clement's is that the route needs an upgrade. However, just because a road is wearing out and in need of repair does not mean it's collapsing or sinking. It isn't.

"Such comments are irresponsible and wrong. Oxfordshire Highways will continue to inspect the High Street and carry out any repairs necessary to keep it in a safe condition before work begins."

Graham Jones, of the High Priority Campaign, which is calling for a reduction in bus numbers and the removal of London and airport express buses, said: "There are some areas where the road isn't in a good state and there's a risk of it sinking.

"We know the road is sinking in places and the need for maintenance work is urgent. But our campaign isn't just about the carriageway, it's about the whole street scene."

David Marcus, managing director of Reginald Davies Jewellers, said: "There are several points on the carriageway that are in very bad condition and I can only think it is because of the buses. Banning cars from the street was supposed to make it more friendly, but we now have so many buses here."

Peter Mann, the county council's assistant head of transport, said: "There are some cellars under the High Street, mainly under the pavement areas, but the deterioration to the road is caused through general use."

Philip Kirk, managing director of Oxford Bus Company, said: "We don't agree that our buses are causing the High Street to sink. There are other areas, for example Headington and Botley Road, that have much higher vehicle usage, without causing the problems experienced in the High Street.

"The council has just announced a review of the OTS and we're very happy to work with them and others. The challenge is to strike a balance between having sufficient capacity on services to carry the vast numbers of people who use buses every day with the other demands of the city centre. "

'There are several points on the carriageway that are in very bad condition and I can only think it is because of the buses'