A Conservative MP accused of rape has agreed to stay away from Westminster, the Commons Speaker said as he urged colleagues not to reveal his identity.
Sir Lindsay Hoyle confirmed the suspect MP has agreed to stay away after the Tory chief whip urged him to do so while the investigation is ongoing.
Because he has not had the whip suspended, the unnamed MP remains part of the parliamentary party and can therefore enter parliament.
The assurance to Sir Lindsay came a day after the Met Police said the man, aged in his 50s, had been held on suspicion of indecent assault, sexual assault, rape, abuse of position of trust and misconduct in public office.
He has now been released on bail.
Boris Johnson's spokeswoman said the prime minister was "shocked to learn of these allegations" and she suggested if the MP was to be charged they would expect to "lose the whip" - meaning they would be expelled from the Conservative Party.
Earlier on Wednesday, Foreign Secretary Liz Truss told Sky News' Kay Burley it was worrying that the "appalling" allegations have been made about a parliamentarian.
Ms Truss said: "I'm very, very concerned about the reports that I have heard. Clearly this is a matter for the police.
"It is worrying that we are seeing these appalling accusations again about a parliamentarian."
Labour's shadow chancellor Rachel Reeves called for a review of rules about whether people accused of serious crimes should be allowed to enter the parliamentary estate.
She told Sky News: "It is obviously incredibly concerning that somebody has been arrested and now bailed for rape, continues to serve as an MP - and although he has been advised not to come to the House of Commons, my understanding is that he is still free to enter the building.
"There is an issue about the culture of our politics, about the vetting procedures, about who can be an MP and stand for public office.
"But parliament also has a duty of care towards other people who work in the building and I'd be very very concerned if this person was still able to come into the House of Commons."
Ms Reeves said the whip should be withdrawn from the MP and that there needed to be a "look at the rules around parliament and about whether somebody accused of such serious crimes should still be able to enter the building".
She added: "This isn't a one-off."
Last month, Imran Ahmad Khan resigned as an MP after he was found guilty of sexually assaulting a 15-year-old boy.
The Sunday Times has reported that 56 MPs face allegations ranging from making sexually inappropriate comments to more serious wrongdoing.
The allegations against the MP who has been arrested cover a period between 2002 and 2009 and are alleged to have occurred in London.
Police said they had received a report relating to the claims in January 2020.
Pressed over whether it was right that an MP arrested for rape should still have the Tory whip, Ms Truss said: "I think it's a matter for the police about whether that individual is named.
"I don't know who it is. I know that the police are looking at it and investigating it and I think we need to wait for the police to conduct those investigations.
"I understand that this individual is not on the parliamentary estate."
A spokesperson for the whips office said on Tuesday: "The chief whip has asked that the MP concerned does not attend the Parliamentary estate while an investigation is ongoing.
"Until the conclusion of the investigation, we will not be commenting further."
It was understood the Conservatives will not make a decision on whether the suspect has the whip suspended until after the police investigation is concluded.
The Prospect union, which represents hundreds of staff working in the Houses of Parliament, said firmer action was needed.
Garry Graham, deputy general secretary, said: "What will it take for parliament to finally take its responsibility to its staff and visitors seriously and suspend access to the estate for parliamentarians under investigation for sexual offences?
"Parliament has the same responsibilities towards its staff as any other workplace and it must live up to them."