Boris Johnson insisted he is “laser-focused” on delivering people’s priorities as he faced the prospect of yet another probe into the funding of his Downing Street flat.

Parliamentary Commissioner for Standards Kathryn Stone has been asked to investigate his conduct over the issue.

Labour MP Dame Margaret Hodge, a former chairwoman of spending watchdog the Public Accounts Committee, has asked for the new investigation into the funding of the refurbishment of the Prime Minister’s apartment.

In her letter to the commissioner, Dame Margaret said: “With this matter the Prime Minister would appear to have repeatedly broken the general principles of the Code of Conduct, failing to be either honest, open or accountable when questioned by the media and in Parliament.

“It has been reported that as much as £200,000 was spent on the redecoration, with some funds originating from the Conservative Party and Conservative Party donors.

“It is therefore unacceptable that the Prime Minister refuses to publicly declare exactly where the upfront costs for this redecoration came from, exactly how much these costs amounted to, and who the Prime Minister is re-paying or has re-paid to cover these costs.”

The commissioner said she would not reveal the names of any MPs under investigation until after May’s elections.

A Commons rule change means she is once again allowed to publish the names of MPs she is investigating for breaches of the code of conduct.

“I believe this step will encourage greater confidence in the parliamentary standards system,” Ms Stone said.

But “in line with guidance relating to the publishing of information prior to the May 2021 elections, I will not publish the names of MPs under investigation until after the elections, in the week commencing May 10 2021”.

Investigations into how the redecoration work was funded are already being carried out by Cabinet Secretary Simon Case, independent adviser on ministers’ interests Lord Geidt and the Electoral Commission.

The Prime Minister has insisted the row over lavish refurbishments to the flat over No 11 Downing Street is a “farrago of nonsense” and “I don’t think there’s anything to see here”.

He has said he “personally” paid for the renovations but has refused to say whether he received an initial donation from the Conservative Party to cover the costs.

The Prime Minister sought to move on from the row as he reflected on the end of a tumultuous parliamentary session which began in December 2019 – taking in the UK’s exit from the European Union and the coronavirus pandemic.

“The changes we’ve delivered have allowed us to take rapid action to protect our country from coronavirus and will make our country stronger, fairer, safer and greener,” he said.

“But there is much more to do, and I will remain laser-focused on delivering the people’s priorities as we work to unite, level up and increase opportunity all across the UK.”

Along with the row over the flat, Mr Johnson faced further embarrassment as it emerged his mobile phone number had been openly available online for 15 years.

A contact number for Mr Johnson was listed on the bottom of a press release when he was still shadow higher education minister in 2006 – a document which was still available online in 2021.

Attempts to call the number on Thursday night were met with an automated message saying the phone was “switched off” and an invitation to “please try later or send a text”.

The Prime Minister’s use of his mobile phone has been in the spotlight after text message exchanges with entrepreneur Sir James Dyson and Saudi Crown Prince Mohammed Bin Salman were leaked.

Downing Street did not deny reports earlier this month that Cabinet Secretary Simon Case advised Mr Johnson to change his phone number because of concerns over the ease with which lobbyists and others from the business world were able to contact him.