Rishi Sunak is facing transparency questions over private jet travel and thousands of pounds in Conservative party donations after they were recorded as coming from a small company linked to a multimillionaire businessman.

Labour has written to two standards watchdogs to ask if any rules have been broken over declarations of more than £88,000 over the past eight months for air travel by the prime minister, and direct funding to the Tory party.

Sunak had declared that air travel worth £38,500 – used for him and eight staff to attend Conservative events in Scotland and Wales in April – was funded by Balderton Medical Consultants, a one-man business whose address on the donations register was given as a west London property near Margaret Thatcher’s former home.

Land Registry records show that the property in Belgravia is owned by a firm based in the British Virgin Islands and Jersey. This firm’s beneficial owner is Akhilesh Shailendra Tripathi, a British-Indian medical tech entrepreneur who made a fortune from an anti-snoring device and who previously donated £114,625 to the Tories in 2021 and 2022.

When the Guardian visited the property, a person who answered the door said it was not the address of Balderton Medical or of its sole director. Asked if the property on Chester Square was the house of Akhil Tripathi, the person said: “Yes.”

A spokesperson for Tripathi’s company, Signifier Medical Technologies, said: “We don’t have any comments or information to offer regarding this situation.”

Sunak’s office and the Conservative party were approached for comment. A spokesperson for the party said: “This donation in kind was processed by the Conservative party, and the information then provided to the prime minister’s office. CCHQ [Conservative Campaign Headquarters] will now review the information provided. If necessary, any administrative errors will be corrected.”

They added: “UK-registered companies which are incorporated in the UK and carry out business in the UK are allowed to donate to political parties and candidates under electoral rules.”

Labour has asked the parliamentary commissioner for standards and the Electoral Commission to examine whether there has been a rule breach over the way the donations were declared. Recipients of donations over £500 are required to take reasonable steps to ensure they know who the actual donor is.

“These rules exist so that, whenever a donation is made to a political party or MP, the public can see exactly who it is coming from,” said Emily Thornberry, the shadow attorney general. “And where mistakes are made in those declarations, it’s essential that they’re corrected and, if necessary, investigated.”

In its letter to the watchdogs, Labour also queried changes in Sunak’s declarations. Tripathi had been named in an entry in May as the donor who covered the cost of the air travel, in which Sunak and his entourage were flown by private jet to Tory party conferences in Scotland and Wales on 28 April. This entry was replaced two weeks later with the Balderton one.

Labour is also calling for scrutiny of a £50,000 donation from Balderton, which was declared by CCHQ to the Electoral Commission in November 2022. It used an address in the Leicestershire market town of Lutterworth, which is the firm’s Companies House address.

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Labour raised further questions about the Tories’ vetting of donations, as Companies House records show Balderton had £28,612 “cash at bank” in its last financial statement at the end of March 2022, despite donating £50,000 cash and £38,500 for the charter flight over the subsequent year.

Tripathi is best known as the founder and CEO of Signifier Medical Technologies, a medical technology company behind a device credited with reducing snoring by more than a fifth by applying electricity to the wearer’s tongue.

The company is an approved NHS supplier and its eXciteOSA unit is on sale in the UK for £648. The same device is the only officially authorised daytime therapy in the US for sleep apnoea, where it retails at a cost of about £1,350 per patient.

A 2021 article in Global Business Leaders magazine described him as a “serial entrepreneur and innovator” and one of the “20 influential business leaders which everyone should know”.

The controversy comes against the backdrop of increasing criticism over Sunak’s use of helicopters and jets for short-haul flights.