Shadow minister Nigel Waterson has been questioned by police after allegations he assaulted two teenage children.
Mr Waterson has been Eastbourne MP for more than 15 years.
The MP for Eastbourne, was arrested after an incident at an address in Bromley, London, on Sunday.
The Tory MP is understood to have called the police himself to report an assault. He was held for nearly 13 hours before being released on bail.
The children did not need hospital treatment. The Press Association says he is not expected to be charged.
BBC South East Today spoke to Mr Waterson on Tuesday and he confirmed he had been arrested. He said he had no further comment to make.
Mr Waterson has been MP for Eastbourne since April, 1992 and has been a high profile campaigner against the closure of maternity services at the town's hospital.
He has been released on police bail until March while investigations into the alleged assault continue.