West Midland politicians have rejected calls for a delay in the planned high speed rail line and urged whichever party wins the next election to build it as soon as possible.

They spoke out after an inquiry said MPs should block legislation allowing construction of HS2 until the Government can prove it has seriously considered other options – including improving connections between cities in the north of England first.

The House of Lords inquiry claimed the Government had failed to make a convincing case for building the £50 billion rail line, which is due to which will link London, Birmingham, Manchester and Leeds.

It was carried out by the House of Lords Economic Affairs Committee, which includes former Chancellor Lord Lawson as well as Labour and Liberal Democrat peers.

They heard evidence from industry experts, local government and business leaders, including Birmingham Chamber of Commerce.

And the peers urged Parliament to vote against legislation known as a hybrid bill which allows HS2 to be built.

But Birmingham MP Andrew Mitchell (Con Sutton Coldfield) said: “As far as we are concerned in Birmingham, all the questions have been answered and the last thing this project needs is further delay.

“Both the major parties have made a very strong case for HS2 and we need to get on with it.”

West Midlands Labour MEP Sion Simon said: “Others can argue about whether it’s the optimum use of national resources. In fact, they can argue about it forever, while the rest of the world’s transport infrastructure pulls further and further ahead of ours.

“From a West Midlands perspective, this is a no brainier: it’s jobs, growth, money in the bank. The only thing people in the West Midlands should be asking is why is it taking so ridiculously long”?

The Committee raised a series of concerns about the business case for the high speed line, which is officially backed by the Conservative, Labour and Liberal Democrat parties, despite opposition from some backbench MPs. UKIP have pledged to put a stop to the planned line.

Below: Gallery of the HS2 Curzon Street station masterplan

Committee chair Lord Hollick said: “We have set out a number of important questions on HS2 that the Government must now provide detailed answers to.

“Parliament should not approve the enabling legislation that will allow HS2 work to begin until we have satisfactory answers to these key questions.”

Ministers say HS2 is needed because the existing network is running out of capacity, but evidence shows long distance trains arriving at and departing from Euston are just 43 per cent full on average, peers said.

The cost of building the line is nine times higher than the cost of constructing similar lines in France, the inquiry found.

Taxpayers are expected to contribute £31.5 billion towards the cost – but peers said there was a case for asking whether the line’s users, who are expected to be mainly business passengers, should be expected to contribute more.

The Committee also warned that the high speed rail network in France, known as the TGV, had benefited Paris the most - and suggested London could be the big winner from HS2.

Campaigners against HS2 welcomed the findings.

Stop HS2 campaign manager Joe Rukin said: “This is surely another nail in the coffin of HS2, which is going to be a massively toxic issue at the upcoming election, as by continuing to support HS2, politicians only demonstrate how out of touch they are.”