Transport for London will not deliver a Metropolitan line extension, says the MP for Watford.

Richard Harrington offered the £73million shortfall needed to make the project work to Mayor of London Sadiq Khan, who has ultimately said "no".

The money would have covered the shortfall needed to start the building work, as well as control over the tracks and and air space, allowing for development in the property above the stations.

But, the Mayor refused this offer and, according to Mr Harrington, suggested a guided bus route.

Mr Harrington said: "I’m very disappointed by the London Mayor.

"I met with him a few months ago and persuaded him to have another look at the huge benefits of the Met Line Extension, not just to the residents of Watford and South West Herts, but to Londoners too.

"He told me he needed more money and so I got two Secretaries of State to guarantee an extra £73 million for the project, making up for the shortfall outlined in his business case.

"On top of that, the government has given him the air rights and control of the tracks.

"This is something that I wanted to deliver for Watford residents.

"I made sure he had the money, as well as the support from the Government, but Sadiq won’t follow through."

Mr Harrington also gained the support of Transport Secretary Chris Grayling, who said it was "hugely disappointing" that the extension will not be delivered, even with the money in place.

A spokesman for the Mayor of London said TfL completed a detailed review and that it would need to more than double the funding commitment made by the previous Mayor in order to complete the job.

The spokesman said: "The previous Mayor committed £49million of London taxpayers’ money to delivering Metropolitan Line extension without working out how much it would cost.

"At the same time he agreed that it would be left to TfL to take on the risk of any additional costs.

"Following a detailed review, TfL estimate that to complete the extension, they would need to more than double the funding commitment they have already made.

"The final cost would be £73.4m higher than the current funding package, and there is a considerable risk that these costs would rise even further."

The spokesman said the Mayor and TfL have taken a "pragmatic approach" to finding a solution but it is difficult to see how the scheme can progress with such financial risk to London taxpayers in its current form.

He added the bus route was something that had been considered but was not a definite alternative to the Met line, which he assured TfL are still hoping to do.

He continued: "The Mayor is determined to ensure an agreement is made which guarantees value for money for London taxpayers – particularly as Londoners are being asked to subsidise a scheme outside London.

"This is yet another example of the incompetent and chaotic approach the previous Mayor took to infrastructure projects – with London taxpayers being asked to pay for a scheme that will benefit people outside the capital."

More updates to follow.