The £56billion HS2 high-speed rail project has an unrealistic timetable and faces major cost pressures, according to the National Audit Office.
A report by the NAO has warned the HS2 project of being too ambitious and that rising costs could result in promises not being delivered.
HS2 Ltd has stated that the first phase of the rail network which will link London with the West Midlands will be completed within 10 years.
Head of the NAO Amyas Morse said: “HS2 is a large, complex and ambitious programme which is facing cost and time pressures.
“The unrealistic timetable set for HS2 Ltd by the Department means they are not as ready to deliver as they hoped to be at this point.”
The next section of the project, running as far as Crewe, is scheduled to open a year after the first phase, with an extension to Manchester and Leeds due to be finished by 2033.
The project is now being considered by the House of Lords after clearing its final stage in the House of Commons.
Responding to the report, HS2 chief executive Simon Kirby said: “The role of the NAO is to challenge projects such as HS2 and through that challenge, improve the way they deliver for the taxpayer. This report does this and we accept that challenge.
“It also, however, recognises the real progress we have made in taking the concept of HS2 and moving it nearer reality.”
The NAO report was written before the referendum vote, so it is not yet known if the project's funding will be affected.
