The Stop HS2 organisation has criticised the Government's claim that HS2 is the only option to remedy over-capacity railways.
Penny Gaines, chair of the organisation, said the line will not open until 2027 and in the meantime will cause years of disruption.
Building HS2 would cause years of disruption at (London's) Euston (station), and other places on the rail network as well as chaos along the route of HS2, with roads being diverted during the build and in some places permanently shut.
However, Network Rail aren't planning to do nothing. They've already announced planned closures on the West Coast Main Line for 2014. It looks like they are positioning themselves to be able to blame others for any problems during these improvement works."
– Penny Gaines, chair of the Stop HS2 organisation
The managing director of Newtork Rail's network operations told the Today programme that any attempt to upgrade existing lines, rather than implement the HS2, would inevitably lead to "very heavy disruption" to services.
Spending £20 billion on upgrading the existing network isn't an alternative. The disruption that would be caused would be a nightmare. This report makes that absolutely clear.
It would only give us a third of the additional capacity which would mean that we would not be able to put more freight on the rail, we would not be able to put additional services into intermediate stations.
An alternative to the HS2 would result in 14 years of weekend rail closures that would "cripple" the three main routes to the north, according to a Government commissioned report out today.
The report by Network Rail and transport consultant Atkins warns that an alternative of improving existing lines would result in 2,770 weekend closures of theEast Coast Mainline, Midland Mainline and West Coast Mainline, in order to complete 144,000 hours of work.
Bob Crow, general secretary of transport union RMT, has described the latest HS2 developments as "political posturing" designed as a smokescreen to delay investment in Britain's existing railways.
Britain's rail system has been dumped in the slow lane for two decades under both main parties through the twin evils of private profiteering and political inertia on key investments like high speed rail.
Today we see that they are back at it again and while the political class carry on showboating we slide further behind the rest of Europe on rail modernisation.
– Bob Crow, general secretary of transport union RMT
Deputy Labour leader Harriet Harman has played down comments by Ed Balls comparing the HS2 project to the Millenium Dome.
Speaking on the BBC's Andrew Marr Show, Ms Harman said Mr Balls did not volunteer the comparison during an interview with a Mail on Sunday journalist.
The shadow chancellor told the newspaper the Dome was a mistake, adding "I think you should learn from your mistakes".
Ms Harman said: "We absolutely support better north-south lines, we are in favour of rail infrastructure for commuters and also for long-distance travellers and freight but not at any cost and what Ed Balls is saying is we have to keep a strong eye on the costs as well as on the benefits."
Treasury Chief Secretary Danny Alexander has told He told the BBC's Andrew Marr Show he is "very confident" that the Government will be able to complete the HS2 project for less than the allocated budget of £42.6 billion.
The real cost is the budget we set out in June this year, £42.6 billion. It hasn't changed at all and that number includes within it a significant amount of contingency.
I'm very confident that as we work through the project and deliver it we'll not just deliver it within that budget but like the Olympic stadium project, under-budget too.
The Labour MP for Luton North, Kelvin Hopkins has joined hauliers and leading supermarket groups and to draw up plans to reopen the former Great Central line instead of committing to HS2, according to the Telegraph.
The paper claims he has handed his plans to individuals including Mr Balls and is understood to have received a positive response.
Senior Labour figures have been secretly considering an alternative route to the HS2 rail project, according to a report in The Sunday Telegraph. It appears the shadow chancellor, Ed Balls, has been provided with a rival £6 billion plan.
The option would reopen a closed line from the 1960s from London to Nottingham, linking Leeds with Manchester.
Cross-party support for the £42billion scheme will be key to the success of HS2, taking into account the long-term funding commitment before trains begin running in 2026.