Labour has demanded all documents relating to Gina Coladangelo's recruitment for her £15,000-a-year job be handed over by the Department of Health as it seeks to hold Matt Hancock to account.
Married aide Ms Coladangelo was caught in an embrace with the former health secretary in footage released by the Sun newspaper on Friday, forcing Hancock to resign on Saturday evening.
But the affair has reignited concerns about the appointment of Ms Coladangelo, who is a friend of Mr Hancock from their Oxford University days.
Married to Oliver Tress - founder of British retailer Oliver Bonas - she was initially taken on as an unpaid adviser in the DHSC on a six-month contract last year, before being appointed as a non-executive director at the department.
The role offers pay of £15,000 a year for 15-20 days of work and is described on the Government website as, in part, "to act in an independent manner bringing expertise, scrutiny and challenge".
It is unclear whether Ms Coladangelo has taken any pay, but a recent advert was posted for four positions before she was appointed in September 2020 which said Mr Hancock would determine their tenure, up to a period of three years.
Alex Runswick, senior advocacy manager at anti-corruption campaign group Transparency International UK, said: "The process for installing non-executive directors in Whitehall should be regulated to ensure any conflicts of interest are properly managed and to provide public confidence in the probity of these appointments."
Ms Coladangelo previously told a BBC Radio 4 profile on the politician the pair met at the Oxford University student radio station, Oxygen FM, where she was a newsreader and he a sports reporter.
She joked that she would tease him that he was not good enough to read the news.
In a letter to DHSC permanent secretary Sir Chris Wormald, Labour's deputy leader Angela Rayner said there were questions to answer over what steps were taken to avoid a conflict of interest.
Ms Rayner said Sir Chris had assured her in a letter in April this year that Ms Coladangelo's appointment to initially provide communications support for Mr Hancock was "short-term in nature, and made in response to an urgent need for specific advice or assistance", and was therefore reasonable.
But she said following revelations that Ms Coladangelo was then made a non-executive director in the department, there were a number of "urgent questions" that needed addressing.
These included exactly what advice or assistance Ms Coladangelo provided Mr Hancock with, the recruitment process she went through, and whether any conflict of interest concerns had been raised.
She also asked whether "at any point during the recruitment of Gina Coladangelo or at any point subsequently did the secretary of state mention or declare any personal relationship between himself and Gina Coladangelo".
Mr Hancock has come under increasing pressure since footage emerged of him kissing his aide in his ministerial office.
Boris Johnson refused to sack his health secretary and his spokesman said the PM considered the matter closed following Mr Hancock's apology.
But instead the Minister submitted his letter of resignation on Saturday.
The Sunday Mirror has reported that Ms Coladangelo would also be leaving her DHSC job, but the department had not confirmed this yet.
Ms Rayner said: "We can't believe a word Matt Hancock says. He has broken the ministerial code and is treating the public like fools.
"We need to know how this appointment was made, whether any conflicts of interest were declared.
"The department must publish all correspondence and documents related to this appointment so the public can see Matt Hancock has broken the rules."
DHSC has been contacted for comment.
