WELSH Secretary Peter Hain yesterday called on the National Assembly to consider road tolls to ease congestion along the M4 corridor.
He believes the planned M4 relief road around the south of Newport could be tolled.
His comments came on the same day Britain's first tolled road opened.
The 27-mile section of the M6 around Birmingham will give drivers the chance to beat the jams by paying £2 to get onto the city's relief road.
Mr Hain said tolled roads could offer motorists more choice and suggested the planned M4 relief road, a project he was involved in planning during his time as a Wales Office Minister, had potential for tolling.
He said, "I know that is a desperately difficult bottleneck getting worse and worse every year since I first proposed it and there could be a point when it could well choke economic mobility."
Motorists would have the choice of going through the Brynglas tunnels on the M4 at Newport at 40mph or paying £1 to travel on the relief road, Mr Hain suggested.
Assembly Transport Minister Andrew Davies, in a statement, said, "Although naturally I am interested in his views, this is a devolved matter and the Welsh Assembly Government will consider this and other proposals in the context of our determination to provide an integrated and uncongested transport network for Wales."
The managing director of Britain's first toll motorway said last night he was delighted to see hundreds of vehicles passing along the new road.
Tom Fanning, head of M6 Toll operator Midland Expressway, said he was ecstatic at the road's successful opening yesterday morning and confirmed the phased opening would continue as planned.
A police convoy slowly led the first vehicles on to the six-lane road in Staffordshire following an opening ceremony headed by the Transport Secretary Alistair Darling.
Access to the motorway - formally known as the Birmingham Northern Relief Road - was limited to local access points to and from Lichfield, Tamworth, Sutton Coldfield, Brownhills and Cannock.
Over the next five days, access will be widened to motorists travelling along the M6 and M42.
Meanwhile, Mr Hain has launched an attack on Welsh local authorities, accusing them of "letting down" the country by arguing against all-postal ballots next year.
The Electoral Commission this week announced Wales would not be among its recommended pilot areas to trial all-postal ballots in elections to the European Parliament, local authorities and community councils next year.
The decision comes after the Welsh Local Government Association said its members could not cope with the pilot and warned to go ahead with the scheme would create an "unreasonable risk" of fraud.
Mr Hain said, "I am very disappointed, particularly as it went against the strong recommendation of Rhodri Morgan and myself.
"I think they are letting down the political system in Wales and I am very disappointed that returning officers have not been willing to carry out this very bold extension of political rights.
"I think we have been let down by some of the local authorities, not all, and some of the returning officers."
Returning officers, who organise elections and counts, argued that with three ballots taking place on the same day they simply could not cope.
A spokesman for the Welsh Local Government Association said, "We are defending the integrity of the electoral process. We felt there was an unreasonable risk by trialing three pilots at the same time."
The Electoral Commission recommendations suggest the North East and East Midlands as the potential trial areas.
The Commission also says Scotland, Yorkshire and the Humber, the North West and West Midlands could be used for pilots despite not meeting all the criteria but concludes Wales, the South-East, South West and the Eastern regions not ready.
Lord Falconer, Constitutional Affairs Secretary, and Nick Raynsford, the Local Government Minister, will have the final decision on the trials.