Sir Keir Starmer has declined Home Secretary Shabana Mahmood’s request for him to sack the immigration minister following a row over a newspaper column.

Mike Tapp wrote an unauthorised article about Home Office policy, which prompted Mahmood’s request for her junior minister to be sacked.

A Home Office source said Mahmood believed the article constituted “freelancing on policy” and was a breach of both collective responsibility and the Ministerial Code.

But a Downing Street spokesperson responded by saying “it is not for any individual secretary of state to determine whether the Ministerial Code has been followed, it is a matter for the prime minister alone”.

The spokesperson also said Tapp has been “reminded of his obligations” under the code, “including collective responsibility and procedures relating to the clearance and presentation of government policy”.

Tapp later wrote on X that he has “a lot of respect for the home secretary and will continue working hard for our country”.

In separate remarks made earlier in the day, Downing Street said the prime minister had confidence in both Mahmood and Tapp, who is a loyal ally of Sir Keir.

The dispute began when Tapp used an article in The Times, external to argue that foreign care workers should be exempt from Mahmood’s plans to change visa rules for migrants already living in the UK.

He wrote: “It is my strong belief that those who have come to the United Kingdom on care worker visas who have played by the rules and have genuinely contributed to our care system should not be required to wait longer to apply for settlement.

“That is the issue I am working hard to address,” he added.

After the article was published on Thursday evening, a Home Office source told the BBC: “Mike Tapp is expected to be sacked for breaching the Ministerial Code.

“He has taken possible ideas that the home secretary and her team were working on, and briefed them as his own to try to win a job in the new administration.”

Reporters were pointed to a passage in the Ministerial Code which says: “The principle of collective responsibility requires that ministers should be able to express their views frankly in the expectation that they can argue freely in private while maintaining a united front when decisions have been reached.”

In response, Tapp said on the social media site X, external: “It’s gone from ‘he broke the ministerial code’ to ‘he stole my idea’.

“I have put my views across on a policy I’ve been working on for months (I have the receipts) in an op ed in The Times. Give it a read, and let’s continue to discuss.

“I won’t be intimidated to drop my views. Stay classy!”

Allies of the home secretary interpreted the reference to “receipts” as a threat to leak sensitive documents.

It is believed this prompted Mahmood to restrict Tapp’s access to government documents and meetings.

Last month, the BBC and others reported that Mahmood had privately told the prime minister she believed he ought to publicly announce plans to leave Downing Street.

Tapp remained a strong public defender of Sir Keir until he set out his resignation plans on Monday.

Earlier, prior to this spat emerging in public, the prime minister’s official spokesman said: “The prime minister and all ministers remain in office and the normal business of government continues.”

Asked about the row, Justice Minister Jake Richards told Radio 4’s Today programme there was an “ongoing debate” about the proposed immigration rules and added: “I think that debate should happen perhaps more privately than Mike – who is a friend and a good man – has shown in the last 24 hours.”

He acknowledged that the government was in “uncertain times” following the prime minister’s departure but urged his colleagues to “take a deep breath”.

“We’ve got a lot of work to be doing in the meantime…we should be doing that instead of some of the silliness we’ve seen over the last 24 hours.”

The government is about to introduce sweeping reforms to the immigration system.

Ministers want to double the time it takes for most migrants to qualify for permanent residence from five to 10 years.

Under the proposals, people who arrived on health and social care visas would face a 15-year wait, while those who relied on benefits for more than 12 months would have to wait 20 years.

Mahmood has defended the plans, saying the “unprecedented” number of people arriving in the UK demands an answer from the government.

But dozens of Labour MPs have opposed the plans, branding the retrospective approach “un-British” and “moving the goalposts”.

Mahmood will seek to drive through the reforms, which will be inherited by the next prime minister, following the resignation of Sir Keir.

Last month Andy Burnham, who is widely expected to become the Labour leader and prime minister, told the BBC he “supports the broad thrust” of what Mahmood is proposing.

In addition, the Immigration and Asylum Bill, which will aim to increase the forced removal of people refused asylum, is expected to be put before the House of Commons next Tuesday and is likely to face stiff opposition from some Labour MPs.