A minister has called for Sir Keir Starmer to release all his messages with Sue Gray in the wake of appointing the Partygate investigator as his chief-of-staff.
Northern Ireland secretary Chris Heaton-Harris said releasing the messages would “clear this up in seconds”.
Labour leader Starmer’s appointment of Gray - whose report in May last year into Downing Street parties during COVID lockdowns was a key factor in Boris Johnson being forced to resign as prime minister weeks later - has been leapt on by Johnson and allies.
They are questioning her impartiality as part of attempts to discredit a separate and ongoing House of Commons committee inquiry into whether he lied to MPs over the lockdown breaches.
Heaton-Harris, who was Johnson's chief whip last year, was asked on Sky’s Sophy Ridge on Sunday programme if he had a problem with the appointment.
Watch: Starmer refuses to say when Sue Gray was first approached for Labour role
He said no, but in an apparent attempt to pressure Starmer, added: "Actually, this is where Keir can help out over his new chief-of-staff by just publishing all the messages and things he might have had with her at that point in time.
"I've dealt with Sue Gray in the Northern Ireland office as a civil servant. I see her as a woman of integrity as well, so I have no issue with that and I think Keir can clear this up in seconds by saying, 'This is what we talked about at that time, there is nothing to see here.'"
It's a topical theme in a week where leaked WhatsApp messages involving former health secretary Matt Hancock, published daily in The Telegraph, have exposed the inner workings of Johnson's government during the height of the pandemic.
Heaton-Harris's call comes after Starmer dodged questions about when Labour first approached Gray.
Starmer would only say on Friday: "I think it has been known for some time that I have been looking for a chief-of-staff and I am very focused on what it is I need from a chief-of-staff."
On the same day, Johnson suggested the appointment of Gray raised questions about her motives while conducting her inquiry into lockdown parties in Downing Street.
He said: "I am sure that people may want to draw their own conclusions about the confidence they can place in the motives behind her, and the way she conducted her inquiry and in her report. I think people may look at it in a different light."
Appearing on the same programme as Heaton-Harris, Labour shadow minister Jonathan Ashworth said hiring Gray shows how seriously the party is taking the prospect of being in government.
Gray, however, is expected to await the decision of the Advisory Committee on Business Appointments (Acoba) before starting the role.
Parliament's anti-corruption watchdog can advise waiting periods before civil servants like Gray can take on other jobs and Rishi Sunak will ultimately make the final decision.