ALMOST £18 million of taxpayers' money was given to the operator of the Severn Bridges for repairs to the old Severn Bridge, the Department of Transport revealed.

A letter from the department to South Wales Central Assembly Members Chris Franks and Leanne Wood revealed that taxpayers have footed the bill for treating corrosion of the main cable and repairs to the cantilever edges of the M48 bridge.

This is because a concession agreement signed with bridge operator Severn River Crossing Plc (SRC) in 1992, stated that the UK Government is liable for latent or pre-existing defects.

The corrosion and damaged cantilever edges are seen to fall within these brackets with the cost of treating them £17,871,666 since 2005/06. This is likely to rise to £21 million by next May.

This is despite tolls to cross both Severn crossings rising to £5.50 for a car and £16.40 for a truck.

The Plaid Cymru AMs hit out, Leanne Wood saying: "While a private firm reaps the profits from the substantial toll charges to get into Wales, the public is left to pick up the tab for essential repairs associated with pre-existing defects."

The AMs cited the £225, 733,000 SRC has made in toll revenues from both bridges since 2006.

Mr Franks called it "astonishing" that tax payers are bearing the cost while Ms Wood called it a "very bad business deal".

She said: "The reverberations of this contract clause are being felt some 18 years later."

A spokesman for the Highways Agency, on whose behalf SRC operates the bridge, said: "The risks for defects that existed prior to the concession were not transferred to SRC as this would have resulted in significantly higher tolls."

He said when the contract was signed, risks could not be quantified and no latent defects were identified until 2005/06. Further costs of £3.8 million are expected for this financial year to tackle the problems.