The European Parliament has launched a disciplinary inquiry into an altercation between Ukip MEPs yesterday, which left one of the party's leadership candidates in hospital.
Ukip MEP Steven Woolfe has accused party colleague Mike Hookem of punching him at the European Parliament in Strasbourg yesterday.
Woolfe was taken to hospital yesterday afternoon after he collapsed following an 'altercation' at a party meeting over his admission that he had considered defecting to the Tory party.
Martin Schulz, the speaker of the EU legislature, wished Woolfe a swift recovery.
"The reported facts are extremely serious," he added in a statement.
"It goes without saying that disrespectful and violent behaviour does not have a place in the European Parliament."
He said the incident could constitute a breach of parliamentary rules and cited rules that refer in part to members acting with "respect for Parliament's reputation", showing "mutual respect" and ensuring they do not "disturb the peace and quiet of any of Parliament's premises".
A breach of the rules can be penalised by a reprimand, loss of voting rights or parliamentary office and a fine worth two to 10 days of subsistence allowance, or from €612 (£552.94) to €3,060.
Woolfe told the Daily Mail that Hookem "came at me and landed a blow".
"Mike was obviously very angry and lost his temper," Woolfe added.
"I wasn't bruising for a scrap. I asked to deal with the matter outside of the room because it was flaring up in the meeting and upsetting everybody, and Mike clearly read that totally the wrong way. It was a completely unexpected incident.
"Mike came at me and landed a blow. The door frame took the biggest hit after I was shoved into it and I knew I'd taken a whack and was pretty shaken."
The two men then returned to the meeting, then went to vote in the main chamber of the EU Parliament.
Two hours after the incident, Woolfe said, he "began feeling woozy and knew something wasn't right so I ran out to get help".
"I started shouting, 'Where is the medical centre?' and was pointed over a walkway bridge," he continued.
"That's the last I can remember. I don't remember anything else. Next thing I know, I woke up surrounded by Parliament staff, lying on the floor and they ran to get my colleague Nathan Gill, who then came with me to the hospital."
Woolfe said doctors told him he had suffered two seizures, one of which lasted three minutes.
Hookem has denied punching Woolfe. "I did not hit Steven and I did not see him hit his head," he said.
Woolfe announced his intention to run for the party leadership on Wednesday, following Diane James' decision to stand down after just 18 days in the role.