A leaked early draft of the report seen by The Times stated that the high-speed railway, which would connect London to Manchester and Leeds, could boost cities in the North and Midlands more than London due to better connections on intercity routes.
It also claimed there are no "shovel-ready" alternative schemes to raise capacity on the existing railway, and "large ticket price rises" will be needed to discourage peak-time travel unless it is built.
But the review, led by former HS2 Ltd chairman Douglas Oakervee, warned that the project's latest cost estimate of £88 billion is expected to increase further. HS2 was allocated £56 billion in 2015.
The review calculated that rising costs have slashed the estimated benefit to taxpayers for every £1 spent from £2.30 in 2017 to as little as £1.30 this year, The Times reported.
The leak appears to contradict media reports suggesting that the review will recommend saving £10bn on the controversial scheme connecting London to the North by cancelling phase 2b between Birmingham and Leeds.
The review was launched by Prime Minister Boris Johnson in August. It was due to be completed this autumn, but the deadline was delayed amid the General Election. Once it has been finalised, the report will be delivered to the new government.
Business and political leaders in the North have previously argued that the greatest benefits to the North will only come if Northern Powerhouse Rail, a £39bn scheme linking the major cities of the North, is delivered alongside HS2.
Asked by The Yorkshire Post if he agreed in September, Mr Johnson said: "That argument I have bought. I get that." He said the main issue was how to get value out of HS2, the controversial project which faces an uncertain future after a government review was launched into whether and how it could proceed.
Henri Murison, Director of the Northern Powerhouse Partnership said: “The Northern Powerhouse Independent Review on HS2 said that there were no identified credible alternatives to HS2 in order to deliver the same capacity, and that it has the potential to unlock greater growth in North and Midlands. It is welcome that their recommendations are mirrored by the governments own Oakervee Review.
“As we await the three major party manifestos, the case has been made for building Northern Powerhouse Rail and HS2 together all the way has never been stronger.
"Now Oakervee recommendations are being debated in public, the time for being equivocal on this issue has run out. Conservative, Labour and Liberal Democrat candidates in the North are committing to back the Connecting Britain campaign of business and civic leaders. All their leaders must unequivocally do the same.”
TSSA General Secretary, Manuel Cortes, has called on Mr Johnson to make clear his party’s commitment to HS2.
He said: “Our concern from the start was that this Review was nothing more than a cosmetic exercise to appease Conservative backbenchers in the shires. Our Labour Party is committed to HS2, Boris Johnson now needs to come clean and tell us whether the Tories fully back it too.
“The Review has been a waste of time and money, leading to needless uncertainty for our members. Now we have the spectacle of a leak during Purdah which means no proper scrutiny can take place.
“There needs to be an inquiry into the leak, but most important of all we must stop the dithering and delay – and get on with building HS2, not only to the North but all the way to Scotland.
“This is our country’s biggest infrastructure project and vital to our future wellbeing. It’s not just about rail travel but jobs in the supply chain and the economic regeneration the project brings to many areas outside London.
“No serious party leader can remain silent on HS2. When it comes to clean and green high-speed rail Britain is decades behind and it’s already taken too long to get out of the slow lane.”
But Harry Fone, Grassroots Campaign Manager at the TaxPayers' Alliance, said: "If these reports are true, this review is in danger of becoming a one-sided stitch up, resorting to old red herrings to keep plans to push ahead with HS2 on track.
"Despite admitting that the budget will have to increase yet again, as the official cost creeps ever nearer to £100 billion, it seems Mr Oakervee has chosen to go over old arguments rather than ask if this project really represents good value for taxpayers."
Phase 1 of HS2 is planned to run between London and Birmingham. It was initially planned to launch in 2026, but a recent report by HS2 Ltd stated that this could be pushed back until 2031.
Current designs involve a second Y-shaped phase launching in two stages: Phase 2a from the West Midlands to Crewe followed by phase 2b from Crewe to Manchester, and Birmingham to Leeds.