Prime Minister Rishi Sunak is being investigated by Parliament’s standards watchdog over a possible failure to declare an interest.
Mr Sunak is being investigated over whether a declaration of interest was “open and frank”, under rules set out by the commissioner for standards.
The BBC understands the probe relates to a childcare firm his wife has shares in.
The commissioner decides whether an MP has broken rules after an inquiry.
A Downing Street spokesperson said: “We are happy to assist the commissioner to clarify how this has been transparently declared as a ministerial interest.”
The Liberal Democrats said the investigation was another example of a Conservative prime minister allegedly “bending the rules”.
“After months of Conservative sleaze and scandal, the public just want a government which is focused on the country, rather than saving their own skin,” Liberal Democrat chief whip Wendy Chamberlain said.
Last month, Mr Sunak faced questions over shares his wife, Akshata Murty, holds in Koru Kids, a childcare agency that could benefit from a new policy unveiled in the spring Budget.
Chancellor Jeremy Hunt announced a pilot of payments for new childminders, with more for those who sign up through agencies.
Ms Murty was listed as a shareholder in one of those agencies, Koru Kids, as recently as 6 March.
Mr Sunak did not mention Ms Murthy’s links to Koru Kids when he was questioned by MPs over the childcare policy at a parliamentary committee hearing on 28 March.
Labour MP Catherine McKinnell asked Mr Sunak whether he had any interest to declare, and in reply he said: “No, all my disclosures are declared in the normal way.”
In a letter to the committee, sent a few days after the hearing, Mr Sunak said his wife’s interest was declared to the Cabinet Office and that an updated statement of ministers’ interests would be due out shortly.
In his letter, Mr Sunak said the the list of ministerial interests “ensures steps are taken to avoid or mitigate any potential conflict of interest”.
The list of ministerial interests is separate to the register of interests for MPs, which says members “must always consider whether they have a conflict of interest”.
The paragraph reads: “Members must always be open and frank in declaring any relevant interest in any proceeding of the House or its committees, and in any communications with ministers, members, public officials or public office holders.”
The commissioner for standards is an independent officer who investigates allegations that MPs have breached Parliament’s code of conduct.
Following investigation, if the watchdog thinks the allegation represents a breach of the code, they can put such cases before MPs sitting on the Committee on Standards, who can decide any sanctions.
The rules around lobbying in Parliament were tightened up in an updated version of the code of conduct, which was published in February following the controversy over paid advocacy work undertaken by former MP Owen Paterson.
New incentives
The pilot of bonuses for childminders was announced in the Budget on 15 March as part of the government’s overhaul of childcare.
Mr Hunt said the government would be “piloting incentive payments of £600 for childminders who sign up to the profession, rising to £1,200 for those who join through an agency”.
The pilot could drive up the number of childminders entering the profession and generate more business for companies such as Koru Kids.
Koru Kids is listed as one of six childminder agencies on the government’s website.
On its website, Koru Kids welcomed the government’s reforms and said “the new incentives open to childminders are great”.
The website says new childminders would get a bonus of £1,200 if they “come through an agency like Koru Kids who offer community, training and ongoing support”.
