Ukip leadership favourite Steven Woolfe is in 'serious' condition in hospital after collapsing following a punch-up with a fellow MEP, reports Daily Mail.
Mr Woolfe dramatically collapsed on a walkway in the European Parliament building in Strasbourg at around 11.20 UK time shortly after the fight with another Ukip politician - understood to be Mike Hookem - at a 'clear the air' meeting.
The married father-of-one - who was marking his 49th birthday today - suffered serious head injuries and is being treated for bleeding on the brain.
Sources said the row was over Mr Woolfe's admission that he had considered defecting to the Tories after being 'enthused' by Theresa May's new direction.
After being told he was a 'joke', Mr Woolfe apparently took off his jacket and challenged Mr Hookem to 'settle this outside'.
Images published by ITV News this afternoon appear to show Mr Woolfe sprawled unconscious on the floor two hours later while someone tries to help him.
Interim leader Nigel Farage, an ally of Mr Woolfe, said in a statement: 'I deeply regret that following an altercation that took place at a meeting of Ukip MEPs this morning that Steven Woolfe subsequently collapsed and was taken to hospital. His condition is serious.'
Aides to Mr Hookem could not be reached today, but sources confirmed to MailOnline that he was involved in the earlier altercation.
Potential rivals for the leadership including Suzanne Evans have wished Mr Woolfe a 'speedy recovery'.
The development comes after the Eurosceptic party was plunged into chaos following the shock resignation of Diane James from its top job.
Mrs James had been in charge for just 18 days but cited 'personal and professional' reasons for her departure, citing a lack of support among the party's MEPs and officials.