As Network Rail deputy chief executive Ian Coucher put the idea to civil engineers yesterday, Mr Fitzpatrick said the £30 billion cost was too high.

Mr Fitzpatrick said the government was committed to improving links to Edinburgh, Glasgow, the north east and the north west of England by investment in existing train services.

At a meeting of the Institution of Civil Engineers yesterday, Mr Coucher suggested the super speed route to Edinburgh or Glasgow, calling at one of York, Darlington or Newcastle, was the way forward.

But in a Commons exchange, Mr Fitzpatrick told former transport minister John Spellar: "The capital cost of constructing a high-speed line between London and Scotland is likely to be £30bn, whichever route is taken.

"Presently, there is no justification for such expenditure."