The opening of Crossrail has been delayed again until the “first half of 2022”, the company building the railway has said.

The railway, from Berkshire to Essex via central London, was originally expected to open fully in December 2018, but repeated delays have pushed it back.

In a statement on Friday, Crossrail said: “The board’s latest assessment, based on the best available programme information right now, is that the central section between Paddington and Abbey Wood will be ready to open in the first half of 2022.”

The new date comes after the team behind the project said last month that the route would not meet its then-summer 2021 target opening.

The update also confirmed that the construction may need as much as another £1.1 billion to be completed.

Covid-19 is one of the reasons behind the new delay, the team said, with social distancing meaning that a maximum of 2,000 people are now allowed on Crossrail sites, which is less than 50% of the staffing levels before the pandemic.

The project’s boss said their “focus remains on opening the Elizabeth Line as soon as possible” and that they have a “comprehensive plan” to open the railway.

Chief executive Mark Wild said: “Delivery of the Elizabeth Line is now in its complex final stages and is being completed at a time of great uncertainty due to the risks and potential impacts of further Covid outbreaks.

“We are working tirelessly to complete the remaining infrastructure works so that we can fully test the railway and successfully transition the project as an operational railway to Transport for London.”

Sadiq Khan’s office said the London Mayor is “deeply disappointed” by the updated schedule.

A spokesman said: “He has asked TfL’s new commissioner, Andy Byford, to review Crossrail’s latest plans, including their estimated additional costs, and to work with the Department for Transport to ensure everything possible is being done to get the central section safely open as quickly as possible.”

Mr Byford also said the delay is “disappointing”.

He added in a statement: “I will now work with my team and the DfT to review Crossrail’s plans.

“I have been very clear that I am committed to getting this railway open safely and reliably as quickly as possible for the benefit of London and beyond.”

The news came on the day the Government launched a new “acceleration unit” designed to speed up road and rail infrastructure upgrades.

Transport Secretary Grant Shapps revealed that a team of specialists will join the Department for Transport to tackle delays to infrastructure projects caused by the pandemic.