Conservative MP Crispin Blunt says he has been arrested on suspicion of rape and possession of controlled substances.
In a statement on X, the Reigate MP said: "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 fact of the arrest requires a formal notification of the Speaker and then my chief whip.
"I have now been interviewed twice in connection with this incident, the first time three weeks ago, when I initially reported my concern over extortion. The second time was earlier this morning under caution following arrest.
"The arrest was unnecessary as I remain ready to co-operate fully with the investigation that I am confident will end without charge."
He added: "I do not intend to say anything further on this matter until the police have completed their inquiries."
Surrey Police said a man was detained on Wednesday morning in Horley.
A police spokesman said: "We can confirm a man was arrested yesterday morning (October 25) in Horley on suspicion of rape and possession of controlled substances.
"He has been released on conditional police bail pending further inquiries."
The Conservative Party said it would not comment as there is a live police investigation.
But Mr Blunt has had the whip suspended pending the outcome of the police investigation, and has been asked to stay away from the parliamentary estate.
Mr Blunt announced in May 2022 that he would be standing down at the next election
The by-election in Tamworth saw Labour overturn a 20,000 majority to take the seat in Staffordshire, which has been held by the Tories since 2010.
The constituency was left vacant by former deputy chief whip Chris Pincher, who quit parliament in disgrace after losing his appeal against a suspension from the Commons following groping allegations.
The Labour Party also took Mid Bedfordshire from the Conservatives in a bitter battle with the Lib Dems.
The contest for Mid Bedfordshire kicked off after the resignation of former culture secretary Nadine Dorries, who resigned in anger at being denied a peerage in Boris Johnson's resignation honours list - but did not officially vacate her seat for 81 days.