A Cardiff MP says poor planning of rail services for rugby fans visiting the city threatens to damage the capital's reputation as a sporting destination.
Rugby World Cup fans have no train home after a crucial October game
Jenny Willott's comments came as it emerged no trains are planned after a vital Rugby World Cup tie on 6 October.
Transport Minister Ieuan Wyn Jones said assembly officials were asking First Great Western about extra trains.
The train operator blamed engineering works but Network Rail said it hoped to be able to "work something out".
Cardiff's Millennium Stadium is hosting four games of the 2007 rugby tournament, including a quarter-final on the evening of Saturday 6 October.
Concerns have been raised about the arrangements for the international supporters travelling home after the game, as the last train to London pulls out of Cardiff half an hour after the match kicks off.
Welsh Secretary Peter Hain said he has asked his officials to write to rail operator First Great Western and Network Rail, claiming it was "essential that transport links are in place to deal with visiting fans".
Ms Willott said she would also be writing to the organisations over an apparent "serious and inexplicable breakdown in communication" between them.
She said: "Over the last 10 years, Cardiff has rapidly become a sporting centre and one of the most popular cities in the UK.
"But basic transport problems that are the result of poor planning, bad management and a lack of communication, threaten to damage this excellent reputation.
"First Great Western and Network Rail... must start talking now so that extra services are in place for the World Cup game and to improve long-term planning and communication so that this doesn't happen in future."
John Pockett, the First Great Western Manager for Wales, said: "Network Rail has a major programme of engineering works on the line between Bristol and Paddington.
"Entry to Paddington is going to be restricted so, unfortunately, it's not possible to do anything."
A spokesperson for Network Rail said: "If First Great Western want to run extra trains, I am sure we will speak to them and try to work something out."
In a statement, Deputy First Minister Mr Jones, who has the transport portfolio in the Welsh Assembly Government, said: "It will be an international showcase for Wales and I'm very keen to see that travel - and all other arrangements - work as smoothly as possible.
"I have asked assembly government officials to discuss with both Network Rail and First Great Western the possibilities of providing extra services to cater for fans travelling from this match."