The Mayor of London has distanced himself from claims that Crossrail could beat its opening deadline.

Last month the chairman of the long-delayed rail link, Tony Meggs, said his team would “meet or beat” the summer 2021 opening date for the central section of the line.

But Sadiq Khan has now said he can’t see how that will be possible in light of delays caused by coronavirus.

Crossrail – which will link Reading, Berkshire, and Heathrow in the west, and Shenfield, Essex, in the east to central and south east London – was originally due to open in December 2018.

Project costs have ballooned from £14.8 billion to as much as £18.25 billion at the last estimate.

Mr Meggs took over as chairman alongside a new chief executive, Mark Wild, to reboot the scheme as hold-ups spiralled.

But there have since been more delays – and there are still concerns about the new opening timetable.

Earlier this month, the Infrastructure and Projects Authority (IPA), a government watchdog, branded the schemes “unachievable”.

The IPA’s annual report on major schemes gave Crossrail a ‘red’ rating – the worst available.

Projects in this category have “major issues” with “definition, schedule, budget, quality and/or benefits delivery” and these problems “do not appear to be manageable or resolvable”.

The IPA assessment dates back to September last year when Crossrail still claimed it could open in 2019 – and the company admitted in November that would not be possible.

But the latest monthly report on the project, by engineering consultant Jacobs, suggests realistic targets remain a problem.

“Crossrail has failed to achieve a programme that has achievable milestones and dependable forecast dates but built around overly optimistic production rates and schedule durations,” the report claims.

Previous Jacobs reports have flagged the same problem, and suggested costs could rise further if there are more delays.

Speaking at Mayor’s Question Time on Thursday (July 16), Mr Khan claimed the chairman’s plan to “meet or beat” next year’s opening date “illustrates the ‘can do’ attitude that the Crossrail team has”.

But the Mayor admitted he is “not quite sure” how Mr Meggs could improve on the target after Covid-19 forced construction work to halt.

“My concern […] is that optimism bias doesn’t lead to expectation that can’t be met,” the Mayor said.

“I don’t think Tony was doing that be fair to him – he was just making the point that [Crossrail is] trying to make up lost ground.”

Liberal Democrat London Assembly member Caroline Pidgeon – who grilled the Mayor on progress yesterday – said clarification was “vital” so Londoners know when the line will “finally” open.

“For too long Crossrail has been plagued by unrealistic progress reports and misleading claims made to the public,” Ms Pidgeon said.

“More than a year and a half after Crossrail should have opened the case for being totally honest with Londoners has never been stronger.”

On site work at Crossrail has now resumed and next month staff will begin a period of intensive work, with shifts running 24hrs a day to speed up progress.

A spokesperson for the railway said coronavirus has impacted work much like any other business.

“Despite significant challenges our focus remains on doing everything we can to open the central section between Paddington and Abbey Wood as soon as we can,” they said.