LONDON — Embattled British Prime Minister Boris Johnson is facing a potential probe into his alleged ties to a U.S. businesswoman.

Authorities in London asked the country's police watchdog Friday to decide whether there are grounds to investigate Johnson for misconduct in public office.

The referral was sent to the Independent Office for Police Conduct. It cites allegations that Jennifer Arcuri and her business received favorable treatment, including access to trade missions and sponsorship money, as a result of her friendship with Johnson while he served as mayor of London.

"These are the ingredients of the offence of misconduct in a public office," said the Greater London Authority's monitoring office, which oversees the conduct of the city's government officials.

"Subject to any explanation provided by you, these matters give rise to a suggestion that there has been a failure to safeguard the public purse and if so that amounts to a significant breach of public trust," the referral said.

A spokesperson for Johnson told NBC News Saturday that "The Prime Minister as Mayor of London did a huge amount of work when selling our capital city around the world, beating the drum for London and the UK. Everything was done with propriety and in the normal way."

Johnson's supporters denounce the referral as a politically motivated attack launched just before his ruling Conservative Party's annual conference.

The city authority that launched the complaint is led by Mayor Sadiq Khan, a Labour Party official.

The allegations were first raised by the British newspaper The Sunday Times last week.

Arcuri told The Sunday Times: "Any grants received by my companies and any trade mission I joined were purely in respect of my role as a legitimate businesswoman."

The newspaper added that she did not comment on the nature of her relationship with Johnson.

Arcuri is an entrepreneur, according to her LinkedIn, and founded the technology companies Innotech Network and Hacker House in the U.K. Her work in the U.S. ranged from being a radio DJ for the Walt Disney Company to operating a Sushi Bar in Morro Bay, California.

The allegations come as Johnson faces increasing political scrutiny over his efforts to take Britain out of the European Union with or without a divorce deal.

Earlier this month he caused an uproar by suspending Parliament for five weeks despite the looming Oct. 31 Brexit deadline.

The U.K.'s Supreme Court ruled unanimously Tuesday that this suspension was unlawful, a humiliating defeat for Johnson that meant the suspension was instantly reversed.

With Parliament back in action, Johnson faced further criticism for using words such as "surrender" and "betrayal" when referring to lawmakers who disagree with his hard-line vision for Brexit.

Politicians across the house condemned the language, which casts members of Parliament as enemies of the people and echoing the countless death-threats they have received as the Brexit debate has intensified.