HS2 needs a major rethink and should not go ahead without a new assessment of its business case, a group of peers has warned.

A report by the House of Lords Economic Affairs Committee warned it is “far from convinced” the new high-speed railway will be built within the £55.7 billion budget.

The committee, which includes former chancellors Lord Darling and Lord Lamont, stated the cost of the project could be cut by reducing the speed of the trains and moving the London terminus.

London train station stock
The group has previously suggested moving the London terminus from Euston station to the west of the city (Philip Toscano/PA)

It claimed construction of HS2 should have started in the north rather than the south, adding the Northern Powerhouse Rail scheme connecting major towns and cities in the region should be completed alongside the high-speed railway.

A number of questions it raised in a 2015 report “have yet to be answered satisfactorily”, the group warned.

Phase one of HS2 is due to open between London and Birmingham in December 2026, before the railway is extended to Crewe, Manchester and Leeds.

HS2 trains will also serve locations on the existing mainline network, such as Liverpool, Newcastle, Edinburgh and Glasgow.

Lord Forsyth, who chairs the House of Lords committee, said commuter services in the north of England are “badly overcrowded” and the region is being “short-changed” by existing plans.

The former Scottish Secretary added: “The costs of HS2 do not appear to be under control.

“It is surprising therefore that the Government has not carried out a proper assessment of proposals to reduce the cost of HS2 – such as lowering the speed of the railway or terminating in west London rather than Euston – which the committee recommended in 2015.

“A new appraisal of the project is required. If costs overrun on the first phase of the project, there could be insufficient funding for the rest of the new railway.

“The northern sections of High Speed 2 must not be sacrificed to make up for overspending on the railway’s southern sections.”

The report is the latest in a series of warnings about the railway project, with concern over its finances and environmental impact.

HS2 is planned to run up to 18 trains per hour at a top speed of 225mph.

Former HS2 chairman Sir Terry Morgan has claimed the project cannot be built to its current specification on budget.

“I think the triangle of scope, cost and time – something has to give,” he said.

An HS2 Ltd spokesman said it will “generate around £92 billion in benefits to the UK economy”.

He added: “We are determined to deliver a railway that is value for money for the taxpayer and a project that will reshape the economic geography of the country.

“We have strengthened our controls and are actively applying lessons learnt from recent infrastructure projects to ensure we have the most cost-effective approach.”