Sir Keir Starmer has declined to commit to building HS2 in full if Rishi Sunak abandons plans to build the high-speed rail route to the North.

The Labour leader instead urged the Prime Minister on Tuesday to “end the chaos” over the future of the project and “get on with it”.

Downing Street has refused to guarantee that trains will run from the Midlands to Manchester after scrapping the Leeds legs already as it seeks to save billions.

But confusion also surrounds the position of Labour if it wins the next general election and forms a government amid concerns over the cost.

Labour sources made clear they do not want to go further than the Government by promising to complete the project in full because they would then need to find additional funding.

Asked if he will commit to building the tracks to Leeds, Sir Keir said the Government is at fault for having cast “doubt” over the infrastructure project.

“We’ve always supported it and I think the Government needs to end the chaos now, make a statement and make clear that it will hold good on the promises it has made,” he told broadcasters during a visit to French President Emmanuel Macron in Paris.

The Labour leader added: “The only doubt that has been cast now, and the only reason we are having this discussion, is because it’s now possible that they are going to fail on yet another infrastructure project.”

It is understood that Sir Keir wants the Government to build tracks to Leeds as well as Manchester.

Labour’s blueprint for potential policies to put to voters committed to “deliver Northern Powerhouse Rail and High Speed 2 in full”.

The National Policy Forum document, agreed by shadow ministers, union leaders and party members, said the move would be “unlocking billions in economic growth, creating decent jobs, slashing journey times and increasing capacity”.

But Labour’s campaign co-ordinator, Pat McFadden, said on Sunday that he needs to “see what this costs” before committing to the full original route as “there may be revised costs”.

Senior shadow minister Nick Thomas-Symonds later promised that the party would build the line “in full”, including to Leeds.

However, shadow Treasury minister Tulip Siddiq went on to raise doubts about the commitment.

“I wouldn’t be a very responsible shadow Treasury minister if I didn’t look at the final costs and if I didn’t make sure that the taxpayer was getting that value for money,” she told Times Radio.

Shadow transport secretary Louise Haigh said the Tories would be committing a “great rail betrayal” if the project does not reach the North, or central London.

The planned railway was intended to link the capital, the Midlands and the North of England but has been plagued by delays and soaring costs.

Ministers confirmed in March that construction of the Birmingham to Crewe leg of the high-speed railway would be delayed by two years and that services may not enter central London until the 2040s.

West Midlands mayor Andy Street said “we absolutely need to stick” to the plan for the line to extend to Manchester.

“There’s a real sort of point of principle here that the Government has to demonstrate that it can deliver on the really big picture moves that will make us more competitive in the long term,” he told BBC Radio 4’s PM programme.

“There is not a business case for building a relatively short line from, as you say, Acton to Birmingham.”