Rishi Sunak is reportedly reviewing how the cost of HS2 can be "controlled", a minister has said as he warned the price tag of the rail project has "roughly tripled" since its conception.

The prime minister has refused to guarantee that the railway line from London to Birmingham will run, as initially planned, to Manchester - where the Tory Party conference will be held this weekend. The HS2 line aims to connect London to the North-West, linking some of the biggest cities including Manchester, Birmingham, and London.

The Government has yet to confirm, however, if the HS2’s final destination will be in central London, with the chief executive of HS2 Ltd stating a lack of funds for completion may mean the rail project will not run to Euston until 2038. In March, the Government announced that the construction of part of HS2 would be delayed by two years to save money. At the time of writing, the only confirmed part of the route will be the Old Oak Common terminus to Birmingham.

No 10 has said ministers will need to balance the interests of “passengers and taxpayers” in considering whether to extend the line to other northern hubs such as Crewe and East Midlands, with the projected cost having shot up past £100 billion.

Home Office minister Chris Philp insisted on Tuesday that no decision has been made on whether to axe or delay the rail project's northern leg amid widespread criticism.

"It's roughly tripled I think since it was first conceived," the policing minister told Sky News.

He added: "No decisions have been taken about the remaining stages of HS2 but I do know the Chancellor and the Prime Minister are looking at how the cost can be controlled."

Mr Philp insisted the people of the North are "definitely not" second-class citizens, as Greater Manchester mayor Andy Burnham claims they are being treated.

"The commitment to the Midlands, the North, the levelling up agenda is absolutely undimmed," Mr Philp said.

A growing number of senior Conservatives, as well as leaders in the North, have been warning the Prime Minister against scrapping the Birmingham to Manchester route.

Former chancellor Philip Hammond told the Times on Tuesday: “We’ve already spent £40 billion [on HS2]. That money’s sunk. The cost-benefit economics strongly point to completing the project. Do we just throw it away and create a white elephant, or press on with a project that will have transformative value for the economy?”

Here we look at the timeline of HS2 delays and U-turns:

January 2009

The Labour government set up HS2 Ltd after evaluating proposals in respect of the cost and benefits of enhancing capacity and connectivity with the new rail line. The first section would connect London and Birmingham by 2020 and cost £7bn.

January 2012

The high-speed rail gets the go-ahead from the Conservative-Liberal Democrat coalition government, with an initial budget of £32bn, inciting strong views in favour and against the scheme.

June 2013

The project continues to fuel concerns among government officials, with costs rising to £42bn.

June 2016

The National Audit Office (NAO) publishes a report on HS2’s progress and finance issues.

The report finds that the project is facing cost and schedule delivery problems and should be delayed by a year.

The NAO also said the HS2 team was looking to reduce costs, with a delay potentially helping them with budget issues.

August 2019

A BBC report finds the Government and HS2 bosses were aware the project was grossly over budget and behind schedule for the past three years.

September 2019

HS2 Ltd chairman Allan Cook does not believe the project can be delivered within its £55.7bn budget and will be delayed.

January 2020

The previous chairman of HS2, Douglas Oakervee, issues an independent review and states the project could cost as much as £108bn.

The NAO added it was uncertain what the final cost of the project could be.

February 2020

Prime Minister at the time Boris Johnson gives the project the green light despite rising concerns.

May 2020

An Independent Construction Commissioner is appointed to oversee HS2 Phase 2a route. However, MPs warn the project has gone “badly off course”.

September 2020

HS2 formal construction begins but is met with some restoration work being “paused”, including Birmingham’s Curzon Street Station, originally built in 1838.

July 2021

MPs from the Transport Committee and the Public Accounts Committee travel to Birmingham for HS2 accountability sessions.

September 2021

There are major concerns regarding the projected increase in time and money, with both MPs stating there is “no clear end in sight” and the Public Accounts Committee adding it is “increasingly alarmed” regarding vital parts of the project.

October 2021

MPs from both sides argue over the Government’s Integrated Rail Plan (IRP), an initiative that aims to transform the rail network in the North and Midlands.

Despite clashes within the Government and ongoing protests, Johnson announces we “will do Northern Powerhouse Rail, we will link up the cities of the Midlands and the North”.

November 2021

The eastern leg of HS2 to Leeds is scrapped with no east-west line linking Leeds to Manchester being built, said the then Secretary of State for Transport, Grant Shapps.

He added that the Oakervee review of HS2 showed a major rethink was needed, with the National Infrastructure Commission report meaning “a flexible approach” was needed.

But the Government is accused of a “great train robbery” by Labour shadow transport secretary Jim McMahon, and he added that ministers have “betrayed” the North.

January 2022

The Oakervee Review is leaked to the Financial Times. It finds that HS2 could cost up to £106bn, but concludes “on balance” that the project should continue.

July 2022

UK ministers come under fire for cancelling a £3bn section of HS2, which would have allowed Scotland to benefit from the rail line.

The SNP describes the move as a “sleekit” and “cowardly”.

Sturgeon and Greater Manchester Mayor Andy Burnham hold private meetings to discuss better alternatives when it comes to axing the Golborne link to take high-speed trains to Scotland.

October 2022

Parts of Euston Road in London would close in early 2023, it was announced, in order to dig tunnels for the HS2, which is “well beyond the point of no return”.

The Government announces phase one of HS2, between Old Oak Common and Birmingham, is due to open around 2030 and the link to Euston is due to open between 2031 and 2035.

January 2023

Activists from the group Daniel Hooper, also known as Swampy, Dr Larch Maxey, Isla Sandford, Lachlan Sandford, Juliett Stevenson-Clarke, and Scott Breen state that justifications of the HS2 project “have gone out the window” after reports the Euston route could be axed due to rising costs.

“It’s been clear to me for a couple of years now that HS2 is gonna get scrapped – our job as protesters is to bring forward the inevitable date when it does by helping to shine a light on it,” said Dr Maxey to the PA news agency.

“As soon as anyone with any common sense looks at HS2, they realise it has no place in a sensible world, we’ve won the argument, there is no argument.”

February 2023

The Department for Transport looks to commission HS2 to rethink its scheme, with the possibility of axing parts of the proposed line due to rising costs, reports The Times.

According to reports, completion of the project could now be as late as 2045.

And a mysterious brown foam began spewing out of the ground at Ruislip RFC, in west London, on the 24th, causing work on the controversial project to be stopped for several hours. It was “most likely caused” by one of the tunnelling machines for the HS2 project. This raised concerns about what might happen if something similar were to happen in a more populous place, such as the inner city.

March 2023

More delays for HS2 are announced by Thurston in order to curb rising costs, with the route’s final destination yet to be confirmed as central London.

Mr Harper said: “We have seen significant inflationary pressure and increased project costs, and so we will rephrase construction by two years, with an aim to deliver high-speed services to Crewe and the North West as soon as possible after accounting for the delay in construction. “

He also announced setbacks to key road projects as he blamed the pressures of soaring inflation and increasing costs.

Thurston said the impact of inflation has directly hit the HS2 project, saying budget issues have been “significant”.

“We are absolutely committed to delivering HS2 trains from London to Manchester and, of course, going over to the east as well,” said Thurston.

“But, of course, we have to look at cost pressures, it’s absolutely right that HS2 focuses on costs, that should be expected of the Government and the taxpayer, we’ll continue to do so.

“But… I am absolutely committed, as is the Secretary of State (Mark Harper) and the entire department, to delivering HS2 and the benefits for this country.”

July 2023

The project is labelled “unachievable” by the Government watchdog IPA, which says it is not deliverable in its current format and slaps the project with a red rating.

The “red” rating was assigned to the plans for the construction of the first two phases by the group in its annual report on big projects. This means that “successful delivery of the project appears to be unachievable” in their opinion.

The report states: “There are major issues with project definition, schedule, budget, quality and/or benefits delivery, which at this stage do not appear to be manageable or resolvable. The project may need rescoping and/or its overall viability reassessed.”

September 2023

Downing Street refuses to guarantee that the HS2 line will run to Manchester amid rumours claiming that Rishi Sunak and Jeremy Hunt are discussing scrapping the project’s second stage.

When asked about speculation that the northern leg could be shelved amid spiralling costs and delays, No 10 suggests that ministers would need to balance the interests of “passengers and taxpayers”.