London, April 17 : UK Prime Minister Rishi Sunak is being investigated by UK Parliament's commissioner for standards over a potential breach of rules relating to the declaration of interests, understood to be related to his links to a childcare firm in which his wife is an investor, media reports said on Monday. The Commissioner, Daniel Greenberg, opened an investigation into the Prime Minister on Thursday last week, an update on the Commissioner's website said, The Guardian reported. The entry says only that it relates to paragraph six of the updated code of conduct for MPs, which states they "must always be open and frank in declaring any relevant interest in any proceeding of the house or its committees". Sunak's wife, Akshata Murty, is listed as a shareholder in Koru Kids, which is among six private childcare providers likely to benefit from a pilot scheme proposed in last month's budget to incentivise people to become childminders, with 1,200 pounds offered to those who train through the agency, The Guardian reported. On 28 March, Sunak did not mention his wife's interest when speaking about the childcare changes before the liaison committee. He was asked by Labour MP Catherine McKinnell whether he had anything to declare. "No, all my disclosures are declared in the normal way," he told McKinnell. It later emerged that bosses from the company attended a Downing Street reception hours after Sunak's committee appearance, The Guardian reported. It is understood that McKinnell raised the issue with the commissioner. Sunak does not list his wife's shareholding on his register of interests as an MP, which MPs are required to update promptly. Downing Street has argued that this is not necessary, because Sunak cited it on a separate register of ministerial interests. This, however, has not yet been published, as it is still being compiled by the new adviser on ministerial interests, Laurie Magnus, The Guardian reported. /IANS