The responsibility for Crossrail failures must be explained by the Government, MPs have demanded.

Passengers have still not been told the root causes for London’s new east-west railway being delayed and over budget, a scathing report by the Commons’ Public Accounts Committee (PAC) stated.

The cross-party committee urged the Department for Transport (DfT) to make clear what it, Transport for London and Crossrail Limited are responsible for in relation to the project.

The Department should also outline “what the consequences have been” for senior officials after the railway failed to open as planned in December 2018, the report said.

Committee members warned that they were “not convinced” trains will begin running next year or that the “additional £2.8 billion of funding provided will be enough”.

The DfT – which is a joint sponsor of the project with TfL – was accused of failing to put in place robust governance arrangements.

The committee added that it was “increasingly alarmed at the continual shortcomings” in the DfT’s oversight of Britain’s railways.

Labour MP Meg Hillier, who chairs the PAC, said passengers have been “badly let down” over Crossrail and it is clear the planed opening date was “unrealistic for some time”.

She blamed the organisations involved for putting a “positive face on the programme long after mounting evidence should have prompted changes”.

She went on: “Wishful thinking is no basis for spending public money and there remain serious risks to delivering this programme, with a revised schedule and costings for completing the work still to be agreed.

“Some £2.8 billion of extra funding has been provided for Crossrail but even that may not be enough.

“It is unacceptable that Parliament and the public still do not know the root causes of the failures that beset this project.”

Mark Wild, who became Crossrail Ltd’s chief executive in November, revealed in January that “none of the stations could have been ready for December” and admitted there were “still thousands of hours of construction work to do in the tunnels”.

Testing of the signalling systems is also taking much longer than expected.

The project’s cost is being met by the Government, the Greater London Authority – including TfL – and London businesses.

Its budget has fluctuated from £15.9 billion in 2007 to £14.8 billion in 2010.

But due to the cost of the delayed opening, a £2 billion Government bailout of loans and cash was announced in December.

Crossrail will be known as the Elizabeth Line when it opens.

Once fully operational, it will run from Reading and Heathrow airport in the west to Shenfield and Abbey Wood in the east, through 13 miles (21km) of new tunnels in central London.