Rishi Sunak has admitted holding a US green card while he was UK chancellor because he had “lived and worked” in America.

Mr Sunak was granted permanent residence in the US – but “immediately returned” the green card when making his first trip to the country as chancellor in October 2021, according to a statement from his spokeswoman.

Labor had urged the chancellor to “come clean” on his use of US residency and family tax affairs after The Independent revealed this week that his wife Akshata Murty had non-dom tax status.

The chancellor’s spokeswoman said on Friday: “Rishi Sunak had a green card when he lived and worked in the US.”

She suggested that Mr Sunak had been paying tax on US income, and had continued to use his green card for US travel, while a member of the UK government.

The spokeswoman said Mr Sunak had not been “presumed to be a US resident just by dint of holding a green card”.

She said he had followed “all guidance and continued to file US tax returns, but specifically as a non-resident, in full compliance with the law”.

The spokeswoman added: “Upon his first trip to the US in a government capacity as chancellor, he discussed the appropriate course of action with the US authorities. At that point it was considered best to return his green card from him, which he did immediately.

“All laws and rules have been followed and full taxes have been paid where required in the duration he held his green card.”

It comes as Boris Johnson denied his team at No 10 had been briefing against Mr Sunak – insisting that he had not known anything about the non-dom tax status used by chancellor’s wife.

Mr Sunak has blamed Labor for the fact that details of his wife’s tax arrangements first emerged in The Independent this week – but some allies say they suspect No 10 has been trying to undermine the chancellor.

The prime minister told a Downing Street press conference: “If there are such briefings, they are not coming from us in No 10 – heaven knows where they are coming from.”

Backing his under-pressure chancellor, Mr Johnson said: “I think that Rishi is doing an absolutely outstanding job,” adding: “I don’t think people’s families should be dragged into things.”

Mr Johnson said he had not known that Mr Sunak’s wife had non-dom tax status – and suggested the chancellor had done nothing wrong when it came to the matter of his US residence.

Grilled about his use of a US green card, the prime minister said: “As I understand it the chancellor has done absolutely everything he was required to do.”

In an interview with The Sun, Mr Sunak said there had been attempts to “smear my wife to get at me” – saying it was “awful”. Asked if he thought Labor was behind a smear campaign, Mr Sunak replied: “Yeah.”

But a Labor source responded: “The chancellor would do better to look a little closer to home. It’s clear that No 10 are the ones briefing against Rishi Sunak.”

Sir Keir Starmer said Mr Sunak and his family will probably “be alright” in the cost-of-living crisis following revelations about the chancellor’s wife’s tax status.

On Friday Labor frontbencher Emily Thornberry pointed to the ministerial code – which mentions that the financial status of ministers’ spouses is relevant because “there can be a conflict of interest” – and suggested Mr Sunak “didn’t declare it properly”.

But the Treasury denied that the code had been breached. “The chancellor provided a full list of all relevant interests when he first became a minister in 2018, as required by the ministerial code.

“The Independent Adviser on Ministers’ Interests has confirmed that they are completely satisfied with the steps the chancellor has taken to meet the requirements of the Code.”