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".
Ukip MEP Steven Woolfe has said he is "feeling brighter" after being rushed to hospital with a suspected brain injury.
Mr Woolfe was taken to a Strasbourg hospital on Thursday following reports he was involved in an "altercation" with another party MEP.
Nigel Farage had said that the 49-year-old, a contender for the Ukip leadership, was in a "serious" condition.
But Mr Woolfe later released a statement from hospital, saying: "The CT scan has shown that there is no blood clot in the brain.
"At the moment I am feeling brighter, happier, and smiling as ever."
He said he is being kept in hospital overnight "awaiting secondary tests to make sure everything is fine".
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?