Mr Sunak ordered an inquiry into the leak of his wife’s tax status on Saturday, as the Chancellor’s allies said officials could be prosecuted for releasing the information, which he had declared to a small number of officials.
A source said: “This will be a more aggressive version of leak enquiries, where it will not only investigate who were the keepers of the sensitive information and who had access to that information, but also who if anyone requested to see it.
“The inquiry will be carried out with a view to potential criminal prosecutions because it is against the law to leak someone’s tax status.”
A source admitted that Mr Sunak would have known the specifics of the investments at the point that he instigated the “blind management” arrangement in 2019, but insisted that the mechanism meant that “from that point on he has no idea whether they would still be there or not.” The Treasury declined to answer questions about the size and composition of the investments, or whether any had links to tax havens.
Only four other ministers declare “blind management” arrangements in the list of ministers’ interests – all of whom are peers.
Sajid Javid, Mr Sunak’s predecessor and a former investment banker, declared no financial interests while he was Chancellor.
Allies of Mr Sunak also hit back at his critics for “somewhat distasteful” comments “speculating on or engaging in a conversation about the death of a woman and what might happen to her estate”.
It comes after it was reported that the Chancellor’s wife would avoid more than £400 million of tax if she was to die, due to a 1950s treaty between Britain and India.
A source said the Chancellor’s detractors should refrain from “assuming what she might do with that estate”.
A Cabinet Office spokesman said: “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.”