The organisation building HS2 is now more 'confident' about how much it will cost and said 'significant changes' have been made following revelations that ministers were warned the project was going overbudget three years ago.
The warning that spending was spiralling was given in May 2016, two months after legislation for the first stretch of the line was approved by MPs.
Campaigners against HS2 have called for the scheme to be scrapped in the wake of the reports.
A government-commissioned review had already opened into whether the scheme should be cancelled over fears it was costing too much.
An HS2 Ltd spokesperson said:“HS2 Ltd and the Government have provided regular updates on the project and there has been extensive scrutiny, including studies and reviews by the National Audit Office and Parliamentary Committees, which are published on their websites.
“Since 2016, we have moved a long way as a project and organisation. We have now appointed a set of world leading civil engineering contractors which enables us to have greater confidence about cost and construction schedules, as well as making significant changes to our management team. Our CEO has spoken publicly for some time about the cost pressures facing the project and we are working closely with our contractors to bear down on cost before major works commence.
“We look forward to working with Doug Oakervee on his review, and ultimately to delivering a transformative rail project for the UK which is value for money for the taxpayer.”
Campaigners across the Wakefield district have been battling against the project for years.
They said it would ruin residents’ lives and offer no benefit to the district.
Following the most recent revelations, environmental campaigner Paul Dainton said: “The documents prove everything that the campaign groups have been stating for so many years.
“Now is the time for cancellation of the scheme.
“The Stop HS2 local campaign believes whoever announces the cancellation of HS2 will win the next general election – that’s how much it means to the local, and national population.
“We do not need a long drawn out investigation or inquiry, we need instant action to cancel this incredibly expensive white elephant now.
“We must not let consultants, and HS2 continue to spend, spend, spend, at the publics expense, when issues like NHS funding, local government health, and children’s services, require immediate renewed investment.”
If it goes ahead, HS2 is likely to affect South Kirkby, Brierly, Hemsworth, Kinsley, Newstead, Fitzwilliam, New Crofton, Foulby, Crofton, Sharlston, Sharlston Common and New Sharlston.
South Kirkby and Moorthorpe Town Council has refused to co-operate with HS2 Ltd over plans to survey land.
And concerns were raised from chiefs at National Trust Nostell over how close the track could be built to the historic site.
The Department for Transport said it kept the public updated on the cost.
A spokesman said: “Like all major, complex projects delivery plans evolve over time.”