Rishi Sunak has declared the childcare agency his wife holds shares in as a financial interest while under investigation over a possible breach of the rules.

The delayed list of ministerial interests published on Wednesday contained for the first time a reference to “a number of direct shareholdings” owned by Akshata Murty.

The Prime Minister’s wife held shares in Koru Kids as far back as March 2019, before Mr Sunak entered Downing Street as chancellor, according to documents lodged with Companies House.

Mr Sunak is under investigation by Parliament’s standards watchdog over claims he broke the MPs’ code of conduct by not declaring the firm that was boosted by a key policy in the Budget.

His team insisted he had followed the rules by declaring it as a ministerial interest, rather than to the Commons.

But the list of ministers’ interests had not been updated for nearly a year until its publication shortly before Prime Minister’s Questions on Wednesday.

Labour leader Sir Keir Starmer had urged Mr Sunak to “come clean” and publish his financial interests to clear up whether there is any conflict of interest.

Under the section for relevant interests held by a spouse or close relative, Mr Sunak’s entry includes his wife’s venture capital company Catamaran Ventures and unnamed “direct shareholdings”.

A note adds that these include her “minority shareholding” in Koru Kids, which Mr Sunak declined to mention when questioned by MPs last month over why one of his policies specifically benefited childminders who sign up through private agencies.

Previous lists have mentioned Catamaran Ventures but never referenced Ms Murty’s other shareholdings. The new register does not state when Mr Sunak first mentioned Koru Kids to officials.

Sir Laurie Magnus, who was appointed by Mr Sunak as ethics adviser in December after the post was left vacant by Boris Johnson and Liz Truss, said he was content any conflicts of interest “have been, or are in the process of being” resolved.

“I am content that any actual, potential and perceived conflicts have been, or are in the process of being, resolved, but it is important that ministers and their permanent secretaries remain alert in the context of their respective portfolios if ministers’ interests change,” he wrote in his report.

The adviser on ministers’ interests explained that the register does not include “every interest that a minister has declared in relation to themselves and their family members”.

“To do so would represent an excessive degree of intrusion into the private affairs of ministers that would be unreasonable, particularly in respect of their family members,” he added.

“The list instead documents those interests, including of close family, which are, or may be perceived to be, directly relevant to a minister’s ministerial responsibilities.”

Deputy Labour leader Angela Rayner accused the PM of preserving a ‘rotten standards regime’ (Dominic Lipinski/PA

Downing Street declined to say if a mitigation has been put in place to alleviate the perception of a conflict of interest over the shares.

The Prime Minister’s press secretary would not say when exactly Mr Sunak first declared Koru Kids, but suggested it was years ago.

“We have been very clear that the Prime Minister has taken his obligation to declare everything very seriously, he has done that for a number of years,” she said.

“Three independent advisers have reviewed those declarations so one would infer by that, that those declarations – including that of Koru Kids – have been made for a number of years.”

Deputy Labour leader Angela Rayner said: “Rishi Sunak is failing to deliver the integrity he promised and has instead chosen to preserve the rotten standards regime of his predecessors.

“There will be no accountability while the Prime Minister continues to mark his own homework on ethics.

“We need stronger rules and tougher enforcement to give the public the transparency and accountability they deserve.”

The ministerial interests list does not necessarily put Mr Sunak in the clear in the investigation by Parliamentary Commissioner for Standards Daniel Greenberg.

The watchdog opened the inquiry under rules demanding MPs are “open and frank” with their interests.

While the specifics of the investigation are unclear, it focuses on declarations surrounding Koru Kids after Mr Sunak declined to name the firm while being questioned by the Commons Liaison Committee.

Labour MP Catherine McKinnell had asked why childminders will get twice the incentive for joining the profession if they sign up with private agencies under the Budget policy.

Asked if he had any interests to declare, Mr Sunak responded: “No, all my disclosures are declared in the normal way.”

The Prime Minister went on to write to the committee to say he would like to “clarify for the parliamentary record that this interest has rightly been declared to the Cabinet Office”.

A fortnight earlier, before the select committee appearance, Chancellor Jeremy Hunt announced a pilot of incentive payments of £600 for childminders joining the profession. The sum doubles to £1,200 if workers sign up through an agency like Koru Kids.