A DECISION on the proposed high-speed rail line to the North has been delayed – but ministers refused to confirm it was to allow a £500m tunnel to be drilled, heading off a Cabinet revolt.

The one-month hold-up will allow Transport Secretary Justine Greening to give “detailed and careful consideration to the issues raised in the recent public consultation”, MPs were told.

But the statement made no reference to newspaper leaks revealing the Government is preparing to spend an extra £500m on a short tunnel in the constituency of Welsh Secretary Cheryl Gillan.

The surprise move – overruling the recommendation of expert engineers who devised the route – would bury 1.5 miles of the track under the beautiful Chiltern Hills, in Buckinghamshire.

Ms Gillan had threatened to resign if the £32bn high-speed rail (HS2) project went ahead as planned through her Chesham and Amersham constituency – and many other Tory MPs are in revolt.

However, supporters of HS2 – to build a 250mph line from London to Birmingham, then on to Leeds and Manchester – believe the hold-up has set a dangerous precedent that could kill the flagship project.

They fear the show of government weakness will encourage other MPs to demand a tunnel in their constituencies, triggering further delays and legal actions.

Under the plans, the London- Newcastle journey time would be slashed from three hours and nine mins to two hours and 37 minutes – because high-speed trains would run from London to Leeds, then switch to conventional tracks.

However, that benefit would not be felt until 2032-33, when phase two is completed to Leeds, following completion of the initial London-to-Birmingham link, by 2026.

Last night, Maria Eagle, Labour’s transport spokeswoman, criticised the failure to mention the apparent plans.

The party has called for a different route, allowing highspeed trains to connect directly with Heathrow Airport by following the M40 – skirting the heart of the Chilterns.

Ms Greening was expected to give the go-ahead to HS2 next week, but her statement yesterday read: “I have concluded that I should allow myself until early in 2012 to announce my decisions.”

Asked why there was no mention of the £500m tunnel, a Department for Transport spokesman said: “I’m afraid we can’t comment on the speculation in the weekend’s papers.”

David Cameron has pointed to HS2 as evidence of the Government’s commitment to reviving the North – although some academics have argued it could widen the North- South divide.