The High Speed 2 project could be delayed by up to one year due to cost pressures, warns the latest report from the National Audit Office.

According to the NAO, the proposed completion date of December 2026 was “too ambitious” as the HS2 Ltd company said that it was only 60% sure that the scheme could be delivered on time.

The report highlighted that HS2 Ltd was asked by the Department for Transport to assess the potential implications of a 12 month extension of phase one, which links the West Midlands to London.

Robert Goodwill, Transport Minister, insists that the programme’s first phase was “on track” to deliver the scheme in the next ten years, says the Financial Times.

There are also cost pressures on the £56 billion project, with first phase estimate costs of £27.4 billion currently exceeding the funding that is available for the scheme by £204 million, while the second phase exceeded available funding by £7 billion.

Rebecca Sheeran, NAO Director said that the Department of Transport has proposed an “unrealistic timetable” for the delivery of HS2 as it was not as ready as they hoped it would be despite significant progress being made over the last three years.

Ms Sheeran added that make it even more challenging to deliver a project which is already viewed as a complex operation.

Meanwhile, Labour MP Meg Hillier, who chairs the public accounts committee, has labelled the findings “concerning.”

Ms Hillier commented that if HS2 was to deliver everything that the government has promised then there are major decisions that must be made.

Also outlined in the report was a review by the Cabinet Office which is looking to bring costs for phase two down by £9 billion.

The report was produced prior to the Brexit vote last week which has put a number of UK infrastructure projects into doubt.