The UK government does not have a convincing case for spending £50bn ($74bn, €68bn) constructing the HS2 high-speed rail link between London and the north of England, according to a House of Lords committee.

The government has yet to prove its arguments that the new line would rebalance the economy away from the south east and boost capacity on the railways, said the House of Lords Economic Affairs Committee. The committee said there were less expensive alternatives available.

"The Government have not carried out a proper assessment of whether alternative ways of increasing capacity are more cost-effective than HS2," said committee chair Lord Hollick, as quoted by the BBC on 25 March 2015.

"In terms of rebalancing, London is likely to be the main beneficiary from HS2. Investment in improving rail links in the North of England might deliver much greater economic benefit at a fraction of the cost. If we're going to rebalance the economy, then we must have a fundamental appraisal of the impact in the North, and that hasn't taken place."

The government has said HS2 would deliver great benefits, including job creation and travel time reductions. The case for the project was "crystal clear," a government spokesperson said.

"It is a vital part of the government's long-term economic plan, strongly supported by Northern and Midland cities, alongside our plans for better east-west rail links confirmed in the Northern Transport Strategy last week," he said.

"Demand for long distance rail travel has doubled in the last 15 years. It is crucial we press ahead with delivering HS2 on time and budget and we remain on track to start construction in 2017."

The British Chambers of Commerce (BCC) welcomed the committee's scrutiny of the project and said the project should go ahead in the interests of British competitiveness.

"If businesses have to wait several years for details to be fleshed out, the UK's competitiveness will be further compromised. There is a convincing case for HS2, as it is the only solution that can deliver the step-chance in capacity that Britain's north-south railways require," said BCC Director General John Longworth in a statement.