Non-dom status has previously caused controversy in British public life, most notably when the billionaire Tory donor Lord Ashcroft revealed he held the designation in 2010.

A spokeswoman said: “Akshata Murthy is a citizen of India, the country of her birth and parent’s home. India does not allow its citizens to hold the citizenship of another country simultaneously.

“So, according to British law, Ms Murthy is treated as non-domiciled for UK tax purposes. She has always and will continue to pay UK taxes on all her UK income.”

Mr Sunak and his wife met at Stanford University, while the Chancellor was studying there on a Fulbright scholarship.

They live together with their children and dog in a £1.5 million mansion in North Yorkshire, and in a flat above 10 Downing Street reserved for the Chancellor of the day and their family.

Mr Sunak has previously been criticised for what his detractors believe are ostentatious displays of wealth, including a £180 “smart cup” that heats his coffee and a £95 of designer flip-flops in staged photographs of him preparing for fiscal events.

This week Sky News reported that he and Ms Murthy had donated £100,000 to his school, Winchester College.

The latest polling shows that his poll ratings have fallen sharply in recent weeks, and he now has a net approval figure of minus 29.

‘Not fair game’

The Chancellor has complained in the past that it is not “fair game” for his political opponents to criticise his wife.

Ms Murthy was previously criticised for Infosys’s operation in Russia after the country’s invasion of Ukraine.

“I think it’s totally fine for people to take shots at me – it’s what I signed up for,” he told the BBC.

“It’s very upsetting and I think wrong for people to come at my wife,” he said.

He added he was “enormously proud” of Mr Murthy, his father-in-law.

“He’s wonderful and has achieved a huge amount,” he said.

On Wednesday, Labour said Mr Sunak must “urgently explain” his wife’s tax affairs.

Tulip Siddique, the shadow economic secretary to the Treasury, said: “The Chancellor has imposed tax hike after tax hike on the British people. It is staggering that – at the same time – his family may have been benefitting from tax reduction schemes.

“This is yet another example of the Tories thinking it is one rule for them, another for everyone else.”