The heavily delayed Crossrail is now expected to open in autumn 2021, according to the outgoing commissioner of Transport for London.

The troubled Berkshire to Essex via central London railway, which is supposed to run through Reading, was originally expected to open in December 2018, however repeated delays have pushed the project back.

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Addressing the London Assembly Budget and Performance Committee on Monday, TfL commissioner Mike Brown confirmed services on the line will not start until at least September 2021.

Mr Brown said: "What we've looked at is a delay to the later stages of 2021 in terms of our business planning assumption.

"Clearly both the chief executive of Crossrail, in my regular discussions with him, the chair and the board of Crossrail, know the imperative of bringing that date as forward as they can possibly and safely do so, because of the imperative of getting the revenue to flow into TfL overall.

"The assumption we've made is, I suppose, at the pessimistic end, but it's at the pragmatic end and you would expect us to take that approach."

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Mr Brown, who has been the commissioner of TfL since 2015, clarified that Europe's largest transport scheme is expected to open between September and December next year.

He added: "These dates are indicative from a business planning perspective, they're not what the plans of the supply chain or of the Crossrail team, which is to bring it forward to the earliest possible date."

He also warned there remains a risk of unexpected delays on the railway, which will be called the Elizabeth Line when it opens.

Crossrail's budget was set at £15.9 billion in 2007, but it is now expected to cost an estimated £18.25 billion.

After the original December 2018 date was missed, a plan to open between October 2020 and March 2021 was announced in April 2019.

TfL has lost between £500 million and £750 million in passenger revenue due to the delays.

Mr Brown confirmed that the latest injection of between £400 million and £650 million into the project, announced in November, would be the last amount of money needed.

An update from the Crossrail board with a more detailed timeline is expected on Thursday.

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The first part of the railway to open will be the central section, with Elizabeth Line trains running between Paddington and Abbey Wood via central London.

All stations on this section are expected to be in operation on the opening day, except for Bond Street, which is delayed because of "design and delivery challenges".

Full services from Reading and Heathrow in the west to Abbey Wood and Shenfield in the east will then commence "as soon as possible", according to Crossrail Ltd.