Conservative MP Andrew Bridgen has been arrested on suspicion of sexual assault and released on bail.
It is understood that the 46-year-old MP for North West Leicestershire was arrested in relation to allegations of assaulting a 29-year-old woman in central London in the early hours of yesterday morning.
Mr Bridgen is a married father-of-two who entered Parliament at last year's General Election and is regarded as being on the right of the party.
Scotland Yard said in a statement yesterday: "A 46-year-old man has been arrested on suspicion of sexual assault against a 29-year-old woman at an address in SW1 in the early hours of this morning.
"He has been bailed to return on a date in mid-July."
Police declined to confirm the identity of the arrested man.