Ukip MEP Steven Woolfe was punched in the face, new medical evidence suggests.
Sources told ITV News that "bruises consistent with a punch" were found by a team of independent experts.
Mr Woolfe was involved in an altercation with fellow Ukip MEP Mike Hookem in Strasbourg on Thursday.
Mr Hookem "absolutely" denies being responsible for Mr Woolfe's injuries and claims he acted in self-defence during a "scuffle".
European Parliament President Martin Schulz has said he will refer an altercation, which caused Ukip MEP Steven Woolfe to collapse,to an advisory committee.
Mr Schulz said he asked for the parliament's committee to deal with the "very regrettable matter" next week as a matter of "urgency".
"The reported facts are extremely serious," he added. "It goes without saying that disrespectful and violent behaviour does not have a place in the European Parliament.
"Moreover, indulging in this kind of conduct might result in a breach of Rule 11 of Parliament’s Rules of Procedures and of Article 1 of the Code of Conduct for Members of the European Parliament."
Sources told ITV News that "bruises consistent with a punch" were found by a team of independent experts.
Mike Hookem insisted he acted in self-defence during a "scuffle" with Ukip leadership favourite Steven Woolfe.
As Ukip and the European Parliament investigate the 'altercation' between Steven Woolfe and Mike Hookem, what could the repercussions be?