Sadiq Khan, Andy Burnham, Tracy Brabin, Oliver Coppard and Steve Rotheram gathered in Leeds yesterday to issue a joint plea to the Prime Minister – telling him he cannot scrap the second phase of the high-speed rail project which is due to link Birmingham and Manchester.

In a joint statement, they said: “This government has said repeatedly that it is committed to levelling up in the Midlands and North.

"Failure to deliver HS2 and NPR will leave swathes of the North with Victorian transport infrastructure that is unfit for purpose and cause huge economic damage in London and the South, where construction of the line has already begun.”

Labour mayors (left to right) Andy Burnham Mayor of Greater Manchester, Tracy Brabin Mayor of West Yorkshire, Sadiq Khan Mayor of London, Steve Rotheram Mayor of the Liverpool City Region and Oliver Coppard Mayor of South Yorkshire, gather at Arcadis in Leeds, to make a unified plea to the Prime Minister not to scale back HS2 any further.

They also said building Northern Powerhouse Rail “in full” – with high-speed lines which run between Liverpool to Leeds, via Manchester and Bradford – must be “a non-negotiable”.

The latest estimates suggest HS2 could cost up to £71bn, after the Leeds leg was axed in 2021. But that figure, which is set in 2019 prices, is expected to rise to £90bn when it is revised later this year.

Downing Street refused to dismiss reports suggesting they will either abandon or significantly delay the second phase of HS2 and scrap plans for a new London Euston station in the centre of the capital.

In their statement, the mayors added: “The UK does not need a new line that only goes from Birmingham to Old Oak Common, which is six miles from central London. This does nothing for the North of England.

Mayor of London Sadiq Khan speaking in Leeds

"The full Y-shaped HS2 plan was designed to deliver economic benefit right across the country not only between the North and London but between Leeds, Sheffield, Manchester and Birmingham. All of these gains look set to be lost if media reports this week are to be believed.”

Mr Sunak may now put back announcing a decision until the autumn statement in November.

Some have been concerned that details coming this week would cast a shadow over the Conservatives’ party conference, which starts on Sunday in Manchester.

There have been indications the Prime Minister could announce a string of regional transport improvements in an effort to limit the political fallout, including bringing forward Northern Powerhouse Rail between Manchester and Leeds.

Downing Street has said there is precedent to delaying aspects of the high-speed rail scheme because of “affordability pressures”, pointing to high inflation.

HS2: Five Labour mayors across UK urge Rishi Sunak ensure project stays on track