The Mayor of London is to be offered £350 million of additional Government funding to complete the late-running Crossrail project.

Rail Minister Jo Johnson said the money is “short term repayable financing”.

He described the action as an “interim measure” which will ensure “full momentum is maintained behind Crossrail”.

The funding will go towards completing infrastructure in the tunnels, work on stations and testing of safety and reliability.

It was announced on August 31 that the capital’s new east-west railway will open in autumn 2019 rather than December this year to complete infrastructure and testing.

The project’s budget was increased from £14.8 billion to £15.4 billion in July due to “cost pressures”. It is being predominantly funded by Transport for London (TfL) and the Government.

Mr Johnson said London will bear “any additional costs via a financing arrangement” because the city is the “primary beneficiary” of the scheme.

He also announced that TfL and the Department for Transport have commissioned an independent review of Crossrail’s governance and a separate review of its finance and commercial position.

Trains were due to operate through the central tunnels from Paddington to Abbey Wood from December, when separate services on the Paddington-Heathrow and Liverpool Street-Shenfield routes would continue.

In May 2019, direct trains from Paddington to Shenfield were due to launch, with the line fully open from Reading and Heathrow in the west to Shenfield and Abbey Wood in the east from December 2019.

Once the service begins it will be known as the Elizabeth line.

Speaking to reporters in Brussels on Friday morning, mayor Sadiq Khan said: “I was angered, disappointed and frustrated when I was told by Crossrail Ltd that the central section of Crossrail wouldn’t open in December as had been promised for a number of years now.

“It’s quite clear that as a consequence of that delay there are additional costs to be expended.

“I have met with the Chancellor, I have spoken on a couple of occasions with the Secretary of State for the DfT.

“As joint sponsors we agreed this amazing project has got to be finished.”

London’s transport commissioner Mike Brown said: “The confirmation of an interim financing package between the Government and the Mayor of London will enable Crossrail Ltd to continue its construction work and vital testing at pace to open the Elizabeth line to passengers as quickly as possible.”

Caroline Pidgeon, chairwoman of the London Assembly Transport Committee, said: “We welcome this announcement by the Government, but it is only a sticking plaster to keep the project going.

“Londoners need to know what work is left to open the line, how much this will cost and ultimately who will pick up the tab. This is a joint project with Government and all partners need to pay their fair share.”