The launch of the Crossrail has been delayed until at least 2020.
The £15 billion rail line across London had previously been due to open this month.
A £1.4 billion bailout was announced for the Crossrail, costing almost £3 billion more than budgeted.
Sadiq Khan, London’s mayor announced the bailout, saying: “It has been increasingly clear that the previous Crossrail Ltd leadership painted a far too optimistic picture of the project’s status.”
“I have ordered the release of all Crossrail board minutes in the last five years to provide transparency to Londoners on their decision-making, and working with the DfT, brought in a new leadership team.”
“With London’s population continuing to grow, our priority must be getting this monumental project completed as soon as possible, with Londoners enjoying all the benefits the Elizabeth line will provide.”
A DfT spokesman said: “Constructive discussions between the government and Transport for London are ongoing on the terms of a longer-term funding and financing package for Crossrail, with London – as the primary beneficiary – bearing any additional costs via a financing arrangement. All parties are aiming to conclude these discussions as soon as possible.”
The new line will link Heathrow, the West End, Canary Wharf and more, carrying an estimated 200 million passengers annually.