A former transport minister who signed off HS2 has told Sky News he wants an inquiry into the chaos of the project “to make sure it doesn’t happen again”.

The northern leg of the high speed rail line – set to run between Birmingham and Manchester – appears to be under threat amid reports the prime minister and chancellor are holding discussions this week on its future due to soaring costs.

Politics Live: Downing Street repeatedly refuses to comment on HS2

Rishi Sunak earlier declined to back building HS2 to the North in the face of warnings by senior Tories not to axe the rail project, hitting out at the “speculation” surrounding its future, but doing nothing to quell fears just ahead of the Conservative Party’s conference.

Former chancellor George Osborne and ex-Conservative deputy prime minister Lord Heseltine were among those saying cutting the Manchester route would be a “gross act of vandalism” and would mean “abandoning” the North and Midlands.

Norman Baker – a former Liberal Democrat MP who worked as a transport minister in the coalition years – said Mr Sunak had an “anti-rail mindset”, and the rumoured scrapping of the northern leg of the line would be “disastrous”.

Speaking to Sky News at the Lib Dem conference in Bournemouth, he said: “Let’s be quite clear about this. If HS2 is cancelled, it’s not simply a question of inconvenience to passengers.

“There’s going to be job losses in the rail industry. And it’s going to be massive reputational damage to this country.

“People are going to say, what on earth are you doing? You’re cancelling your environmental policies, you’re pulling out of the European Union, you can’t build a railway. Just what is happening with Britain these days?”

Mr Baker – who now works at the Campaign for Better Transport – said people wanted “more HS2, not less HS2”, but criticised the project for being “very badly handled”.

He added: “It’s been hugely expensive. It’s been out of control financially. And we need to have in conjunction with HS2 going head to Manchester and indeed to Leeds as well, we have a proper inquiry as to understand why this has happened and to make sure it doesn’t happen again.”

However, the Lib Dems’ transport spokesperson in the Lords, Baroness Randerson, had concerns an inquiry would cause further delays.

Committing her party to the “full” HS2 project, the peer told Sky News: “Every time the government changes its mind, every time the government trims a few hundred yards, a mile or two off, one end or the other, they are pushing up the cost per mile and they are fatally undermining the economic arguments for it, the economic impetus for it, and its potential economic success.

“If you keep chopping and changing, playing the ‘hokey cokey’, as someone put it… then you are going to put in uncertainty, you’re going to drive up the costs and people are going to lose their mission on it.”

But instead of an inquiry, she called for a “complete review”, adding: “It needs to be reinstated at the heart of government transport strategy, and then it will serve the north of England in the way it was intended to do, to level up.

“I don’t think we need anything that will impede its progress. We need to get on with it. But what we do, what we do need to do, for the sake of any future project, we need to make sure these mistakes aren’t made again because we have to have consistency.

“We are the nation that invented the railways. Now, 200 or so years on from that and we seem incapable of building a modern railway.”

Read more:
What is HS2 and why are parts being delayed?
Why are so many people upset with rail project?

HS2 was first touted by Labour in 2009, but it was the coalition government that signed off the plan, designed to connect the south, the Midlands and the North of England with state-of-the-art infrastructure.

If the Manchester leg is axed it would be the latest watering down of the project, with the eastern leg to Leeds scrapped entirely and work between Birmingham and Crewe delayed due to the impact of inflation.

Some estimates have put the total cost at over £100bn, while the project has been rated “unachievable” by the infrastructure watchdog.

Pushed on the rumours during a visit to a community centre in Hertfordshire on Monday, Mr Sunak said: “We’re absolutely committed to levelling up and spreading opportunity around the country, not just in the North but in the Midlands, in all other regions of our fantastic country.”

He said that transport is “key” to that vision, “not just big rail projects, but also local projects, improving local bus services, fixing pot holes”.

Pressed for a yes or no answer over whether the northern leg would go ahead, Mr Sunak said: “This kind of speculation that people are making is not right. We’ve got spades in the ground, we’re getting on and delivering.

“Downing Street made clear that he was hitting out at the nature of the speculation, rather than suggesting any of it was incorrect.”

Number 10 refused to provide further details but said there is precedent to delaying aspects of the high speed rail scheme because of “affordability pressures”, pointing towards high inflation.

The prime minister’s official spokesman said that Mr Sunak “always listens to both sides of debate, and it’s for him to make final decisions”.

The uncertainty has fuelled anger among leaders in Manchester, who have sent an “urgent” letter to Mr Sunak warning “the North of England should not have to pay for the government’s mismanagement of the HS2 budget”.

Manchester’s Labour Mayor Andy Burnham and the city council leader Cllr Bev Craig are requesting a meeting with the prime minister as a “courtesy” before a decision is taken, in which they will state “in the strongest possible terms that HS2 should not be scrapped”.