Crossrail might not launch until March 2021

London's multi-billion pound Crossrail project has pushed back its launch date again and may now not open until March 2021.

Plans for an east-west line across the capital have repeatedly been delayed since missing the original target date of December 2018.

Crossrail said on Thursday that it had now identified a "six-month delivery window" for the central section of the line between Paddington and Abbey Wood, with a midpoint at the end of 2020.

However, even then, the line's Bond Street station will not be ready because of "design and delivery challenges".

The central section of the route, known as the Elizabeth line, will link the West End, the City of London, Canary Wharf and southeast London - with an initial 12 trains per hour during the week.

Crossrail said that once this opens, full services from Reading and Heathrow in the west to Abbey Wood and Shenfield in the east will begin as soon as possible.

It said the central section works were expected to be delivered within a funding package agreed by the mayor, Transport for London and the government last December, when up to £2bn of extra money was made available.

At that time it was said that no trains would run until 2020 at the earliest.

Crossrail's budget had already been increased from £14.8bn to £15.4bn last summer.

Announcing the latest timetable delay, Crossrail said "many risks and uncertainties" remained in the development and testing of the train and signalling systems.

It said it now had a "robust and realistic plan" to put the project back on track.

The project's chief executive, Mark Wild, said: "I share the frustration of Londoners that the huge benefits of the Elizabeth line are not yet with us.

"But this plan allows Crossrail and its contractors to put the project back on track to deliver the Elizabeth line.

"Crossrail is an immensely complex project and there will be challenges ahead particularly with the testing of the train and signalling systems but the Elizabeth line is going to be incredible for London and really will be worth the wait."

Crossrail's chairman and previous chief executive both resigned late last year .