One of two UKIP MEPs allegedly involved in an altercation at the European Parliament building in Strasbourg has become embroiled in a furious row with parliament president Martin Schulz.
Mr Schulz has reported Steven Woolfe and Mike Hookem - who were both members of UKIP at the time of the incident - to the French authorities over the incident earlier this month.
He told the house on Wednesday that evidence suggested Mr Hookem had hit his colleague - something he has always denied.
Mr Hookem has now threatened to sue the president over his remarks.
The incident left Mr Woolfe in hospital after he suffered two seizures following the confrontation.
He claims he fell backwards and hit his head after he was punched by Mr Hookem but Mr Hookem has denied hitting him during the row.
Mr Schulz told the European Parliament that the "version of facts given by the two members diverged substantially" and that the row appeared to have "happened in the absence of witnesses".
But he said the evidence suggested Mr Woolfe collapsed as a "result of an attack on the head".
He said that on advice from the European Parliament Advisory Committee on Code of Conduct he had reported the matter to police and would decide how to sanction both men after the investigations.
He said: "It also stressed that given the seriousness of the facts and their possible criminal implications, further evidence is needed to clarify this matter.
"As a result, I have decided to follow the recommendation of the advisory committee, and I have referred this matter to the competent French authorities."
In an angry exchange this afternoon, Mr Hookem challenged Mr Schulz to repeat his claims outside the parliament, where he is protected from being sued for defamation, so he could take him to court.
He said: "Can you both leave this building where you don't have parliamentary privilege and repeat them so I can take legal action against you."
Mr Schulz responded by saying: "I would have no problem at all to see you in court and would be pleased to do so."
"What I find regrettable is that as President I have to report that one man struck another, that's the real scandal here," he said.
Mr Woolfe, who was previously seen as front runner for the UKIP leadership, resigned from the party shortly after the incident.
He has spoken of how he suffered two seizures, partial paralysis and loss of feeling in his face and body as a result of the altercation and said he had made a complaint to police.
However, Mr Hookem denies punching Mr Woolfe and posted a picture on Twitter of his hands pointing out there were no bruises.
