MP Crispin Blunt has been arrested on suspicion of rape and possession of “controlled substances” but says he is confident he will not be charged.
The former Tory minister for prisons, who has represented Reigate since 1997, said he would "co-operate fully" with Surrey Police after being held on Wednesday morning.
He added he had been interviewed twice over the incident, the first time three weeks ago when he "initially reported my concern over extortion".
Police have not said if the controlled substances were drugs, as tests are being carried out.
After identifying himself, Mr Blunt had the Conservative whip suspended pending the outcome of the police investigation, meaning he is now an independent MP.
Mr Blunt wrote on social media: "It has been reported that an MP was arrested yesterday in connection with an allegation of rape. I am confirming that MP was me.
"The arrest was unnecessary as I remain ready to cooperate fully with the investigation that I am confident will end without charge.
"I do not intend to say anything further on this matter until the police have completed their inquiries."
Who is Crispin Blunt?
Crispin Blunt has been Conservative MP for Reigate since 1997 and has remained as a backbencher for much of that time.
The 63-year-old had previously announced he would not be standing for re-election at the next general election, which is likely to be next year.
Prior to his political career, Mr Blunt served in the British Army but has worked for the Tories since the early 1990s. He had two children with his ex-wife Victoria Jenkins and he is also the uncle of the British actress Emily Blunt.
What roles has Crispin Blunt had?
In addition to his role as a local MP, Blunt has held two roles within Tory governments.
Under the Cameron government he was Parliamentary Under-Secretary of State for Prisons and Youth Justice from 2010 to 2012. Then, he was Chair of the Foreign Affairs Select Committee from 2015 to 2017.
Will he resign as an MP?
The Tory Party has declined to comment on Mr Blunt's arrest.
It has not been stated if there will be a recall petition or a byelection to reassign his Reigate seat.
