REPAIRS to the old Severn Bridge at Aust are to be funded by the taxpayer.

Transport campaigners are angry that the company which operates the toll bridge under a concession from the government will not have to pay a penny towards the estimated £25million cost of halting corrosion in its support cables.

"If they have a concession to run and operate the bridge then we don't see why they shouldn't also be responsible for the maintenance," said David Redgewell, Bristol area spokesman for the Transport 2000 lobby group. "Otherwise what was the point of privatising it in the first place?"

The rusting cables will not be replaced but measures will be taken - including installing industrial dehumidifiers - to arrest the corrosion.

Until the work is carried out,lorries weighing more than 7.5 tonnes will be restricted to one lane in each direction.

The bridge, which is 40 year old this year and now carries the M48 motorway to Chepstow, recently underwent a £3million inspection funded jointly by the Highways Agency and bridge operators Severn River Crossing.

Highways Agency spokesman Robin Miller said the company took on the concession only about 10 years ago and the proposed course of action was reasonable in the circumstances.

"This is not a problem which just sprung up," he said. "It was there before the company took over the concession."