Rail companies have warned that England needs a new high speed rail link linking Birmingham to London because the West Coast Main Line will soon be full.
The chief executive of Eurostar urged the Government to build high-speed links across the country - starting with a new service b etween London, Birmingham and Manchester.
And the chief executive of Virgin Trains, which runs services on the West Coast Main Line, warned that passengers would suffer severe overcrowding as soon as 2011, as the existing network ran out of capacity.
They were giving evidence to a Commons inquiry into the future of the rail network.
The Government published a White Paper on the rail industry last year, and has launched a review of options including re-opening disused lines or building new ones.
But Tony Collins, chief executive of Virgin Trains, claimed Ministers did not understand how urgent the problem was.
The Government was predicting that overcrowding would become a serious problem on the WCML in 2014 but Virgin believed passengers numbers were growing so quickly that it would be an issue by 2011, he said.
Mr Collins told the MPs: "I could see us hitting those passenger volume and over-crowding levels on the West Coast on our services three years earlier than the White Paper suggests we will get there."
He added: "They are forecasting on average a real growth in passenger volume of about three per cent per annum. They then predict the overcrowding levels would get to an unacceptable level by around 2014.
"Currently as an industry we are achieving twice that rate of real growth so we are achieving about 5.9 per cent of real growth per annum and there is no reason to suggest, even with a slight downturn in the economy, that that type of growth will not continue for the fore-seeable future."
Later in the hearing he told MPs: "It is not a question of shall we have a high speed line at the expense of the current system; I think we need a high speed line and we need to continue to invest in the current system as well to put more capacity in.
"I think there is a huge amount of suppressed demand in the market because we are already at the limit of capacity."
Richard Brown, chief executive of Eurostar, said Britain needed a network of high speed rail lines, starting with a new service linking London to Birmingham and the North West.
"I think there is an emerging agreement that London, Birmingham, Manchester would be the first, but that needs to be part of a wider vision as to what the network could be to make sure you do not build bits which then do not contribute to a wider network in the longer term."
A major review of Britain's transport network in 2006, produced for the Government by former British Airways chief executive Rod Eddington, appeared to rule out high speed rail lines, concluding that the benefits would be "relatively modest".
But last year the Department for Transport announced high speed rail links were back on the agenda.
The possibility of a new line will be considered as part of a review which will also consider re-opening old lines such as the Great Central Main Line, which ran from London's Marylebone Station to Manchester via Rugby in Warwickshire and closed in 1966.