Boris Johnson has committed a “clear breach” of the ministerial code by not clearing his new role writing a column for the Daily Mail first.

The committee that vets ex-ministers’ appointments says he informed them only half an hour before the news emerged.

The Mail said the first column by the former prime minister, for Saturday’s paper, would appear online later.

The newspaper was one of Mr Johnson’s staunchest supporters when he was in No 10.

Mr Johnson has stood down as an MP, but is still required to seek advice from the Advisory Committee on Business Appointments (Acoba) on new jobs for the next two years.

In a statement, Acoba said: “The ministerial code states that ministers must ensure that no new appointments are announced, or taken up, before the committee has been able to provide its advice.

“An application received 30 mins before an appointment is announced is a clear breach.

“We have written to Mr Johnson for an explanation and will publish correspondence in due course, in line with our policy of transparency.”

The committee, chaired by Conservative peer Lord Pickles, has no powers to punish MPs – or former MPs – who have broken the rules but can issue public rebukes.

An Acoba spokeswoman told the BBC “newspaper columns are not considered significantly problematic”, but Mr Johnson was still meant to seek its advice.

The Daily Mail Online Twitter account described Mr Johnson as “one of the wittiest and most original writers in the business”.

In a video shared by the paper, he said: “I am thrilled to have been asked to contribute a column to the Daily Mail.

“It is going to be completely unexpurgated stuff.

“I may even have to cover politics, but I’ll obviously try to do that as little as possible unless I absolutely have to.”

The clip also features a compilation of shots of Mr Johnson in Downing Street, the House of Commons and out jogging.

In February, the total was nearing £5m.

Now that he has stood down as an MP, he will not have to declare his earnings in the register of members’ interests.

The committee previously found Mr Johnson broke the rules after taking up a £275,000 a year column with the Telegraph weeks after standing down as foreign secretary.

It said it was “unacceptable” Mr Johnson had not sought its advice before signing the contract.

His Telegraph became an important platform for his opposition to then-Prime Minister Theresa May’s Brexit plans, and for building support for his own leadership ambitions. He stopped writing it when he entered Downing Street in July 2019.

Paul Dacre, editor in chief of the Mail titles, was rumoured to have been nominated for a peerage by Mr Johnson, but was reportedly one of the names removed during the House of Lords vetting process.

Meanwhile, Mr Johnson has asked his supporters not to vote against a report that found he deliberately misled Parliament over Partygate.

Several of his allies, including Nadine Dorries, had said they would oppose the Privileges Committee’s findings in a Commons vote on Monday.

Its main recommendation is that Mr Johnson should be suspended from Parliament for 90 days, but he has already resigned as an MP.