The Mayor of London must “take a personal interest” in Crossrail, and push for greater transparency, a London assembly member has said.

Keith Prince, the Conservative transport spokesperson, said lack of scrutiny had allowed problems with Transport for London's (TfL) Elizabeth Line to go unchallenged, leading to the current delays.

His criticism came as Sadiq Khan wrote to the Assembly’s transport committee with details of changes he has made to ensure better progress on the project.

But Mr Prince said the changes did not go far enough, and called for Crossrail board meetings to be held in public.

He said: “The Mayor talks about transparency but he never learns a lesson – we know that one of the fundamental problems with Crossrail that led to delays was that there was no transparency.”

“I have a lot of faith in Mark Wild to lead the project, but I want the Mayor to show more personal interest in what’s going on.

It was very clear he didn’t have a clue what was happening – and I’d be rather embarrassed as Mayor of London to admit I don’t know what’s going on with Europe’s largest infrastructure project.”

Crossrail was originally set to open in December last year, but could now be delayed until 2021.

The new line will run from Reading and Heathrow through central London to Shenfield and Abbey Wood, connecting key stations including Paddington, Liverpool Street and Stratford.

In his letter to the transport committee, the Mayor who also responded on behalf of TfL emphasised the importance of the line, and acknowledged the effect of hold ups.

He said: “I remain frustrated and angry at the delay to Crossrail and the impact this is having on millions of Londoners who expected the Elizabeth line to open in December 2018.”

Mr Khan said a new management team with the right skills to lead the project, alongside greater scrutiny at TfL board meetings, would ensure that mistakes were not repeated.

But Florence Eshalomi, who chairs the transport committee, expressed concern that the Mayor’s response did not address the cause of initial errors.

She said: “It’s disappointing to see that blame for the project is still being passed from pillar to post and that no stakeholder so far has been willing to accept their responsibility for the delay."