The Government is looking to slice around 100km per hour off the top speed of the controversial High Speed Two (HS2) rail connection proposed between London and Birmingham.
Officials at the Department for Transport are understood to have asked the state-owned body overseeing HS2, if it agrees with criticisms that Government had focused too much on the need for speed.
This follows an interview in Rail magazine with Rob Holden, chair of the High Speed One link between the capital to the Channel Tunnel, in which he questions whether 400kph trains are needed on HS2.
He argued that 300kph, which is HS1's top velocity, would be sufficient in an area as small as the UK, and that the Government was unnecessarily trying to compete with speeds in other countries.
The news comes ahead of tomorrow's judicial review of the project, brought about by campaigners who say that £33bn HS2 makes no economic sense and that it will ruin the landscape.
The London-to-Birmingham trip would take 49 minutes in 400kph trains, against more than 80 minutes today.
A Transport department spokesman said that there were no plans to reduce the maximum speed of HS2 but the route is "kept under constant review".