Transport Secretary Chris Grayling has issued a warning to Conservative leadership contenders who try to curry favour with party activists by promising to scrap the HS2 high speed rail line.

Speaking to the Birmingham Post, he said: “My gentle advice to anyone wanting to be Prime Minister is, before you take a decision to cancel HS2, just have a conversation with business and political leaders in the cities in the North and Midlands, and you may find it’s not quite such a good idea.”

There has been speculation that Tories hoping to replace Theresa May as leader could attempt to win support from party activists by promising to scrap the controversial £55.7bn project.

And many opponents of HS2 have suggested that cancelling it could free up money to improve transport services in the North.

But Mr Grayling insisted it was wrong to suggest HS2 was preventing other transport projects from going ahead.

He said the Government was already funding transport improvements across the country, and backing plans for a rail network in the North of England, called Northern Powerhouse Rail.

“This is not an either/or situation.

“There are things that we need to do now, which we are doing, that enhance the capacity and quality of our transport system ... HS2 and Northern Powerhouse Rail, those are the next stage."

Transport Secretary Chris Grayling in the House of Commons

There is more criticism of HS2 today (May 16), when the House of Lords Economic Affairs Committee publishes a report warning: "The costs do not appear to be under control".

The authors include former Labour Chancellor Alistair Darling and former Conservative Chancellor Norman Lamont.

Responding to the report, Mr Grayling said: "They may claim the funding is out of control. I don’t know how they would know the funding is out of control because HS2 has a budget and I have been very clear to the HS2 team, ‘you live within your budget’.”

While the Prime Minister has said she is committed to building HS2 in full, a number of top Tories have come out against it.

Former Brexit Secretary David Davis this week launched a report by the Taxpayers’ Alliance claiming 28 other transport schemes could go ahead if HS2 was scrapped.

Former Work and Pensions Secretary Esther McVey said in April that the case for HS2 “gets weaker” each day.

Chief Secretary to the Treasury Liz Truss used an interview in the right-wing Spectator magazine to cast doubt on the project. She said: “What really drives local economies is transport around counties, transport into cities. That’s what makes a difference to why a business decides to locate somewhere.”

And Cabinet Minister Andrea Leadsom, the Leader of the Commons, told a meeting of the Cabinet that HS2 should be scrapped, according to a report in the Times.

HS2 construction work continues apace in Birmingham city centre, where a new station will be built at Curzon Street.

Former Foreign Secretary Boris Johnson is a longstanding critic and has called on the Government to prioritise improvements to transport links between the east and the west instead of HS2, which runs north to south.

But as the Transport Secretary suggested, politicians representing the North of England have consistently backed HS2.

In January, more than 40 prominent figures from the Midlands and the North signed an open letter calling on leaders of every major political party to commit to completing the high speed rail line.

They included Ian Ward, the Labour leader of Birmingham City Council.

The open letter said: “HS2 Phase Two will extend the benefits of this vital piece of infrastructure to more than 25 million people – over a third of the UK’s population – across the East Midlands, the North and Scotland.

“These people and places should not be denied the job and growth opportunities that HS2 brings.

Signatories included Steve Rotheram, Mayor of Liverpool City Region, and Judith Blake, Leader of Leeds City Council.

The new HS2 station in Curzon Street, Birmingham
The planned HS2 station in Curzon Street, Birmingham

Nick Forbes, the Labour leader of Newcastle City Council, said in February “HS2 is vital to our region’s long term prosperity, and to cancel it would be a betrayal of the North that would have decades long consequences.

“Cancelling HS2 would undermine everything the Government has set out to achieve with the Northern Powerhouse.

Greater Manchester Mayor Andy Burnham said that both HS2 and Northern Powerhouse Rail were essential, also in February.

He said: “Be wary of this HS2 debate. They’re trying to make us choose between good North-South or East-West links. The truth is the North needs both.”

Conservative West Midlands Mayor Andy Street also backs HS2.