Boris Johnson casts fresh doubt on '£100billion' HS2 rail project saying it will cost 'an awful lot of money'

Boris Johnson today cast fresh doubt on the HS2 rail project - suggesting it will cost 'north of £100billion'.

The PM hinted at a rethink on the massive scheme - which would affect his own Uxbridge constituency - saying the government would review whether funding could be 'better spent'.   

Interviewed on LBC radio, Mr Johnson insisted he is not 'temperamentally hostile to big infrastructure projects'. 

But he said: 'If you come in and there's a project of north of £100billion probably, you have to ask yourself, it's only responsible to the taxpayer to ask whether it's being sensibly spent and that funding is being prioritised right.'

Presenter Nick Ferarri pointed out that the government's current estimate for the project costs was £88billion. 

Mr Johnson said: 'Looking at how these things go, it probably will come in at over £100billion, that's my guess. 

'But at the moment, you're right, it's £88billion. That is still an awful lot of money.' 

An independently-led government review recommended last month that ministers commit to the full proposed network connecting London, Birmingham, Manchester and Leeds.

The leaked conclusions admitted that it is 'not affordable' within the £56billion budget set in the 2015 government spending review.

The new estimate of £88billion is likely to be increased again, the report noted.

In September, Transport Minister Grant Shapps said the first phase of the railway between London and Birmingham would be delayed by up to five years.

That section of the line was due to open at the end of 2026 but it could now be between 2028 and 2031 before the first trains run on the route.

The second phase has been delayed. That route - from Birmingham to Manchester - was due to open in 2032-33 but that has been pushed back to 2035-2040. 

HS2's top line speed is about 250mph, though most trains will only run at up to 225mph - still among some of the fastest in the world. 

Mr Johnson also refused to back off his famous vow to 'lie down in front of the bulldozers' to prevent Heathrow expansion.

'I don't see much sign of any bulldozers yet,' he said. 'I would have to find some way of honouring that promise.'