Boris Johnson reportedly wrote a letter recommending American businesswoman Jennifer Arcuri for a job as the head of a technology quango when he was mayor of London.
Amid a storm over his association with the former model, leaked emails seen by the Sunday Times showed Mr Johnson was listed as a reference in her application for the role at Tech City.
Ms Arcuri was said to have been a 27-year-old student at the time of applying for the £100,000 a year job.
In an email leaked to the paper, she allegedly later wrote: “I still have the letter of rec from Boris. hahaha. To think that we asked him to write us a recommendation for the CEO of Tech City is just hysterical.”
She listed “Boris Johnson, Mayor of London” as a reference on the application, according to the paper.
The report adds to mounting questions about the Prime Minister’s past links with Ms Arcuri.
Last month, Mr Johnson was referred to the police complaints body to assess whether he should face a criminal investigation over his association with the businesswoman.
It follows reports by the same paper that Ms Arcuri was given £126,000 in public money and privileged access to three foreign trade missions led by Mr Johnson while he was mayor.