Jonathan Edwards has been questioned on suspicion of assault.
A Welsh MP has been arrested by police on suspicion of assault.
44 year Jonathan Edwards - who represents Carmarthen East and Dinefwr for Plaid Cymru - was questioned by Dyfed powys Police on Wednesday.
The dad of two from Ammanford has since been released on bail.
Plaid Cymru say he's been temporarily expelled from the party while the investigation continues and will have to sit in Westminster as an independent.
A Plaid Cymru statement said: "The party whip has been withdrawn pending the conclusion of a police investigation.
"Mr Edwards has accepted this course of action and is complying fully with the police enquiries.
"It would be inappropriate for the party to comment further at this time."