Conservative frontbencher Nigel Waterson was arrested on suspicion of assaulting his teenage son and daughter yesterday, media reports suggest.
The Daily Mirror newspaper claims Mr Waterson was held for 13 hours on Monday after being taken from his home in handcuffs.
It alleges his children, who are in their early- to mid-teens, were questioned by police and given a medical examination after the incident took place. Neither required treatment in hospital.
The Metropolitan police said a 58-year-old man had been arrested following reports of an assault at around midnight on Monday.
"He has been released on bail to return to a south London police station on a date in early March pending further inquiries," a spokesperson said.
"Following police attendance an allegation was made concerning previous alleged offences on a second victim."
Detectives from the Met's Child Abuse Investigation Command are investigating the incident.
Mr Waterson is the Conservatives' shadow pensions minister and shadow minister for older people and represents Eastbourne, Willingdon and East Dean in parliament.
The allegations are more bad news for the Conservative party, which has been embarrassed by Derek Conway's apparent overpayments to his son.
Last September Croydon Central MP Andrew Pelling was arrested over allegations he had assaulted his pregnant wife Lucy, prompting his suspension from the party.
The crown prosecution service decided not to bring charges against Mr Pelling the following month.