Transport for London’s (TfL) commissioner has refused to resign over the delayed Crossrail project.

Mike Brown declared that he is “fit to be in position” and has the “full support” of mayor Sadiq Khan.

Crossrail, which will be known as the Elizabeth Line when it opens, was due to launch in December but now could be as late as 2021 due to a series of problems.

A report published by the London Assembly Transport Committee on Tuesday stated that Mr Brown, who has held the role at TfL since September 2015, “altered key messages of risk” on deadlines on the project which were sent to Mr Khan’s office.

In one example, references to problems being caused by signals and train software were removed, with a senior TfL official saying it “was amended by Mike so that the setbacks appeared less serious”.

The report recommended that Mr Brown, appointed by Boris Johnson when he was mayor and paid at least £350,000 in 2017/18, “reflect(s) on whether he is fit to continue to fulfil his role”.

Giving evidence to the committee on Thursday, Mr Brown said: “I’m not reflecting on whether I’m fit to be in position. I believe I am.

“I’ve got the full support of the mayor and that’s the end of that issue from my point of view.”

Asked if he regretted warnings about the progress of Crossrail being “watered down” in emails to Mr Khan, the commissioner insisted that “messages reached the mayor consistently” and “emerging risks … were very explicitly highlighted” in meetings with the mayor during 2018.

Mr Khan’s office has said he has “every confidence” in Mr Brown, adding that the previous leadership of Crossrail were responsible for providing “inadequate information” about the delays.

Crossrail’s delay has resulted in a row over when Mr Khan knew the railway would not open on time.

He claims he only found out on August 29, two days before Londoners were informed, but Crossrail Ltd’s former chairman Sir Terry Morgan insists the mayor was aware of problems at least a month beforehand.

Sir Terry resigned as chairman of HS2 Ltd and Crossrail Ltd – a TfL subsidiary – in December.

The project’s budget has fluctuated from £15.9 billion in 2007 to £14.8 billion in 2010.

But due to the cost of the delayed opening, a £2 billion Government bailout of loans and cash was announced in December.

Once fully operational, the Elizabeth line will run from Reading and Heathrow airport in the west to Shenfield and Abbey Wood in the east, through 13 miles (21km) of new tunnels in central London.