The cost of using the Severn bridges is set to rise again, amid claims that drivers have already paid for the cost of the second road crossing twice over.
Car drivers travelling back into Wales face a £5.30 toll
Welsh Lib Dem leader Mike German wants tolls scrapped, saying figures show the cash collected on both bridges into Wales from 1996 to 2006 was £684m.
The Second Severn Crossing, which was completed in 1996, cost £300m to build.
But the operators said toll rises on 1 January, up 20p to £5.30 for cars, were strictly complying with legislation.
Mr German, who has obtained the figures from the Welsh assembly library, said the charges for motorists on the M4 crossing into Wales should be abolished.
"The Severn bridge tolls are a barrier to Wales' prosperity and a real disincentive to people visiting Wales or setting up business opportunities," said Mr German, who is South East Wales AM.
"One of the best ways to close the prosperity gap between Wales and England would be to remove the financial barrier at the border."
From 1 January, the cost of driving a car into Wales will increase from £5.10 to £5.30, small goods vehicles and small buses will go up from £10.20 to £10.60 and heavy goods vehicles and buses from £15.30 to £15.90.
TOLLS COLLECTED SINCE 1996
1996 - £47,154,568
1997 - £51,112,112
1998 - £55,240,910
1999 - £59,831,779
2000 - £60,995,760
2001 - £66,513,803
2002 - £70,544,522
2003 - £64,412,838
2004 - £66,371,474
2005 - £69,499,056
2006 - £72,008,062
Total revenue - £683,684,884
Source: Welsh assembly library
The first bridge, which carries the M48, opened in 1966 and is currently the subject of £20m maintenance work to stop corrosion.
The second bridge opened 30 years later.
Mr German said with the annual increase of charges, motorists could end up paying for the second Severn crossing three times over before the tolls are eventually scrapped.
Under the Severn Bridges Act 1992, when the tolls reach £1bn in 1989 prices, the bridge reverts to public ownership.
"The more people travel over the bridge, and the higher the tolls rise, means that the day is coming when the bridge will revert to public ownership," Mr German said.
"The government could then decide to scrap the tolls and put the Welsh economy on an equal footing with its neighbours in and around Bristol."
John Warman, the organiser for Cast (Campaign Against Severn Tolls), said: "I maintain that with the large fuel increases road users have had to cope with, it is going to be a hard year for the economy and road users in Wales."
Severn River Crossing general manager Jim Clune said: "Severn River Crossing amends the tolls at the start of each year in strict compliance with the Severn Bridges Act 1992 and upon an order from the secretary of state."