Tory backbencher Mark Pritchard has been arrested and bailed over an allegation of rape.
The Wrekin MP voluntarily attended Holborn Police Station on Tuesday evening over an incident alleged to have taken place in central London.
He was arrested and then released on police bail four hours later.
A Scotland Yard spokesman said: “We can confirm that a 48-year-old man voluntarily attended a north London police station on Tuesday, December 2 where he was arrested, following an allegation of rape in central London.
“He has been bailed to a date in early January 2015 pending further inquiries.”
A letter from Met officer Sandra Looby to Speaker John Bercow said: “I write to inform you that on December 2 Mark Pritchard MP was arrested at 6.14pm at Holborn Police Station in London by Metropolitan Police Service officers.
“Mr Pritchard was questioned by police and released on police bail later the same evening at 10.16pm.”
A Conservative Party spokesman said: “This is a police matter. It would be inappropriate to comment while an investigation is taking place.”
Conservative MP Mark Garnier told the BBC: “I know Mark reasonably well, I like him.
“I last saw him on Tuesday when I gather he was arrested. These are incredibly, incredibly, serious allegations.
“Clearly, he must answer to the rule of law.”
Mr Pritchard, who entered the Commons in 2005 after a career in marketing, has been a prominent figure on the Eurosceptic wing of the Conservative Party.
He served as secretary of the powerful Tory 1922 committee for two years until 2012, and is a member of parliament’s joint national security strategy committee.
Before his arrest, Mr Pritchard was in the House taking part in a debate on the peace process in Colombia.
In September, Mr Pritchard disclosed that he had been targeted by a journalist as part of the sting that led to Tory minister Brooks Newmark resigning over explicit “selfies”.
He has apparently withdrawn a complaint to the Independent Press Standards Organisation (Ipso) after agreeing a confidential settlement.
Mr Pritchard divorced his wife of 15 years, Sondra, last year.