Boris Johnson was not aware of "specific allegations" against Chris Pincher when he was promoted to deputy chief whip, a Cabinet minister says.
Mr Pincher was suspended as a Conservative Party MP earlier this week over allegations he had groped two men.
He now faces six new claims of inappropriate behaviour stretching back several years, which he has denied.
Work and Pensions Secretary Therese Coffey defended the PM, saying he took "decisive action" to suspend the MP.
Ms Coffey told the BBC that "to the best of my knowledge" Mr Johnson was not aware of specific allegations about Mr Pincher, saying she had not spoken to the prime minister directly and had received the assurance from the No 10 press office.
Earlier, she told Sky News Mr Pincher's appointment in February had gone through a vetting process "like normal".
It comes after a number of fresh allegations involving Mr Pincher and No 10's handling of the claims were reported by newspapers this weekend.
The Sunday Times reported that in 2018 Mr Pincher made unwanted advances towards a male Tory MP, who passed on his account of what happened to No 10.
Elsewhere in the papers:
- The Sunday Times reported Mr Pincher had placed his hand on the inner leg of a male Tory MP in a bar in Parliament in 2017. The newspaper reported Mr Pincher also made unwanted advances towards a different male Tory MP in 2018 (mentioned above) while in his parliamentary office, and towards a Tory activist in Tamworth around July 2019
- The Mail on Sunday carried allegations he had made advances against an individual a decade ago, and that a female Tory staffer had tried to prevent his advances towards a young man at a Conservative Party conference
- The Independent published allegations from an unnamed male Conservative MP that Mr Pincher groped him on two separate occasions in December 2021 and June this year.
He did not respond to the BBC but denied the allegations to newspapers.
Mr Pincher, who remains an independent MP for Tamworth in Staffordshire, quit as Tory deputy chief whip after he was accused of drunkenly groping two men at a private members' club in London on Wednesday.
No 10 initially suggested Mr Johnson considered the matter closed, but later suspended the MP from the party after he was reported to Parliament's independent behaviour watchdog.
The prime minister had been coming under pressure to act from some senior Tory MPs and opposition parties to suspend Mr Pincher. A government source later defended the speed with which Mr Pincher was suspended, saying No 10 had acted swiftly after the complaint was lodged.
On Sunday, Labour's shadow business secretary Jonathan Reynolds told Sky the party had been motivated by "what is politically expedient over what is right".
Former Conservative Party chairman and home secretary Lord Baker said it is "unlikely" Boris Johnson is "the right man" to lead the party.
He told BBC Radio 4's World This Weekend the questions around the party's leadership had become "dominant" and party needed unity.
Meanwhile, No 10 has not denied a claim by Mr Johnson's former chief aide, Dominic Cummings, that the PM referred to the former deputy chief whip as "Pincher by name, pincher by nature" before appointing him.
Downing Street's justification for appointing Chris Pincher seems to hang on the lack of a formal complaint.
It hasn't (so far) appeared to deny that Boris Johnson had any knowledge at all about some of the rumours surrounding him.
So, this will, in the end, come down to what his MPs make of that as a judgement call.
Was it right to stand by an ally when nothing had been formally proven?
Or should he have been more much more cautious when appointing someone who would, after all, be dealing with the welfare of other MPs?
It's worth noting that it is the prime minister who decides who to appoint to his government, so this was, ultimately, his call to make.
And elsewhere, Tory MP Craig Whittaker has denied suggestions in the Sunday Telegraph that he left his role in the whips' office in February in opposition to Mr Pincher's appointment, saying he stood down over health issues.
What happened when?
Wednesday 29 June: Chris Pincher was seen "extremely drunk" at London's Carlton Club for Conservative Party members, witnesses later told the BBC
Thursday: Mr Pincher resigns as deputy chief whip, telling the PM he "drank far too much", after allegations emerge that he groped two men at the club
Friday: He is suspended as a Conservative MP after being reported to Parliament's behaviour watchdog
Saturday: Mr Pincher says he is seeking professional medical support and is "truly sorry for the upset I caused"
Sunday: New allegations emerge against the MP, which he denies