Plaid Cymru MP for Carmarthen and East Dinefwr Jonathan Edwards has been arrested on suspicion of assault.
The 44-year-old politician has now had the party whip withdrawn by Plaid Cymru pending the conclusion of a police investigation, which effectively means he is suspended from the party.
A Plaid Cymru spokesperson said: "On 20 May, Jonathan Edwards MP was arrested following a report of an incident.
"The party whip has been withdrawn pending the conclusion of a police investigation.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 enquires.
"It would be inappropriate for the party to comment further at this time."