Falkirk MP Eric Joyce has been bailed by detectives investigating an alleged late-night brawl at a House of Commons bar.
Mr Joyce, 52, was arrested on suspicion of assault, and re-arrested on suspicion of actual bodily harm while in custody at Belgravia police station, central London.
He left in a waiting taxi shortly after being released.
Serjeant at Arms Lawrence Ward - who is responsible for security and keeping order in the Commons - has confirmed that the Independent MP would be subject to an indefinite alcohol ban in parliamentary bars.
A Metropolitan Police spokesman said: "A man aged in his 50s, arrested on Thursday 14 March on suspicion of assault in connection with a disturbance in a bar within the House of Commons, has been bailed to return to a central London police station on a date in late March.
"He was further arrested while in custody on suspicion of actual bodily harm."