A flagship £3.55 billion north-south rail link across London may not be delivered on time with passengers facing a wait of up to 30 years before they can use it, a damning report by MPs has revealed.

In the highly critical report, MPs questioned the way in which the Department for Transport (DfT) has sought to advance the  Thameslink extension and cast doubt on the official 2018 completion date.

The House of Commons public accounts committee said that the department’s award of a £1.6bn private finance contract for new trains for Thameslink was delayed by significantly more than three years.

In addition it has been suggested that overall, passengers would have to wait for around 30 years for the scheme to go ahead.

“We remain concerned about the department’s skills and capacity to complete Thameslink by 2018, alongside its ambitious wider portfolio of programmes and projects,” the report stated.

MPs added that DfT “suffers from a shortage of strong project management skills” and that the core Thameslink team of just five seemed “too small for a programme of this scale, compared with teams for other complex government projects.”

Public accounts committee chairwoman Margaret Hodge was critical of the planned methods for franchising the operation once it was completed and doubtful of the projected train delivery timetable and the initiative used to pay for it.

She said: “The procurement of new trains through a £1.6bn PFI deal has taken over three years longer than expected and the timetable and approach for letting the new franchise have been revised.

“The planned completion date has been put back to 2018 but meeting the timetable for delivering the new trains will be very demanding and risky. 

“We are also sceptical about using PFI to fund this project.”

The contract for providing the Thameslink trains was infamously given to German engineering giants Siemens by the government, while British engineers at Bombadier were left out in the cold.

Rail union RMT said the news that the trains would probably be delivered late held no surprises.

RMT general secretary Bob Crow said: “This report is a complete vindication of everything that RMT has said about the chaotic Thameslink fleet replacement programme which took train-making in Britain to the brink of collapse. 

“Never again must there be a repeat of this expensive fiasco which was cooked up by the same government department that brought us the rail franchising shambles.”