Plans for a high speed railway line to the Midlands and the North have been branded a "political trophy project" by Labour former business secretary Lord Mandelson.
In a withering attack on the HS2 scheme, Lord Mandelson warned it was based on "flimsy evidence" and would "suck the very life blood" out of the rest of the country's rail network.
He told the Lords that Labour's frontbench were right to have become "more sceptical" about the multimillion-pound project.
Lord Mandelson had previously backed the plans but announced a U-turn earlier this year because of escalating costs.
"I have been an ardent pro-railway supporter all my adult life. But it is precisely for that reason that I do not support HS2," he told peers.
"I think the sheer cost of it will suck the very life blood out of the rest of the country's rail system."