Jennifer Arcuri will hand over her diaries to investigators in a move which could prompt a fresh probe into Boris Johnson 's links to the American businesswoman, it has been reported.
The monitoring officer at the Greater London Authority (GLA) will inspect parts of her diaries which detailed her relationship with the Prime Minister while he was mayor of London, The Observer reports.
Her links with the Tory leader came under public scrutiny last year over allegations she received favourable treatment for her business ventures during his eight-year stint as mayor.
Ms Arcuri alleged earlier this year in the Sunday Mirror that she and the PM had a four-year romantic relationship when he was mayor.
Arcuri claimed she had a four year relationship with Johnson
In March she claimed they first slept together hours before he sat between his then-wife Marina and Princess Anne at the opening of the 2012 London Paralympics.
She says they met up once a week at the height of the affair, and she sent him arty topless picture s. She admited: “I loved him. I adored him.”
But she describes him as a “cowardly wet noodle” for not standing by her in the row over her presence on foreign trade trips.
Mr Johnson avoided a criminal investigation after the police watchdog found no evidence he had influenced the payment of thousands of pounds of public money to Ms Arcuri, or secured her participation in foreign trade trips that he led.
However, the Independent Office for Police Conduct said it "would have been wise" for the former mayor to have declared their "close association" as a conflict of interest.
The GLA's oversight committee is investigating whether he conducted himself in a way that is expected of people in public office.
The Observer reported that Ms Arcuri has now agreed to be interviewed for the first time, and share notes she made in her diaries of their telephone calls and conversations.
Arcuri said she "loved" the Prime Minister
A government spokesman told the Observer last week: "As mayor, Boris Johnson followed all the legal requirements in the Greater London Authority's code of conduct at the time."
The GLA confirmed to the PA news agency it had received a complaint from Labour's deputy leader Angela Rayner, after some of Ms Arcuri's diary extracts were published by the newspaper last week.
A spokesman said: "The GLA's monitoring officer has received a complaint from Angela Rayner MP relating to the conduct of Boris Johnson (when he was mayor of London and occupant of the mayor's office for policing and crime) and has recorded it in line with the GLA's procedures.
"Recording a complaint does not mean that there has been any assessment or consideration of the merits of the complaint or that the complaint has any substance at this stage of the process.
Arcuri has agreed to share her diary entries with investigators
"The monitoring officer is seeking further information in order to assess the complaint."
The Observer reported that Ms Arcuri told the GLA: "I am prepared to show you or your investigators copies of the relevant pages."
Mr Johnson has previously said his dealings with Ms Arcuri were "done with complete propriety" and previously welcomed the IOPC findings, as he criticised the "vexatious claims" against him.
Previously, Mr Johnson's press secretary said there was "no case to answer" following the findings by the IOPC.
"This work has been done – public time, money and effort has been spent looking into whether or not there's any wrongdoing and it was found that the Prime Minister, the then London mayor, has no case to answer," she said.
The GLA's monitoring officer will now review the complaint to see whether it is a "serious complaint", and therefore whether it can be referred back to the IOPC.
Ms Rayner tweeted: "If Boris Johnson made promises of support to Jennifer Arcuri because of his personal relationship with Ms Arcuri it is vital that the GLA refers this new evidence to the IOPC and that the IOPC reviews its decision to rule out a criminal investigation.
"We need a full investigation into whether the processes behind the public funding for Ms Arcuri's business and her presence on publicly-funded trade visits was the result of misconduct in public office by Boris Johnson."