Police have arrested a 61-year-old man over online threats against Tory MP Louise Mensch.
The Metropolitan Police said the man was arrested in Gloucester in connection with an investigation into "malicious communication and threats made via email and a social networking site".
Mrs Mensch claimed earlier this week that "morons" had threatened her children by email.
A Scotland Yard spokesman said the police central e-crime unit and officers from the Palace of Westminster had been involved in the arrest.
The spokesman said "The 61-year-old was arrested at an address in the Gloucester area on suspicion of sending malicious communication.
"He has been taken into custody at a Gloucestershire police station where he remains."
Mrs Mensch, who writes chick-lit novels under her maiden name Louise Bagshawe, has three children and was elected as MP for Corby last year.
On Monday she posted a message on Twitter claiming that her children had been threatened by email and said she had passed the message to police in the House of Commons.
She added: "I don't bully easily, kids. Or in fact at all."