"Aborting" his leadership campaign on Monday and quitting the party, Woolfe said he had "come to the conclusion that UKIP is ungovernable without Nigel Farage leading it and the referendum cause to unite it."

His statement made reference to the UK Independence Party's high profile leader Farage who is credited with playing a key role in Britain's vote to leave the EU.

Woolfe said UKIP, which has just one MP in Westminster but 22 members of the European Parliament, was "riddled with infighting" and "proxy wars between rival camps." He added that the party's national executive committee was not fit for purpose.

The 49-year-old plans to sit as an independent MEP until Britain leaves the EU.

Remembered for fight

Woolfe, who was seen by many as the obvious candidate to be the next UKIP leader, is still recovering from an altercation on October 6 during a party meeting at the European Parliament in Strasbourg, which left him in hospital for several days.

Woolfe alleges he "received a blow" from fellow UKIP MEP Mike Hookem and collapsed. Hookem has denied striking his colleague.

After the altercation, party members said Woolfe had angered some in the meeting by admitting he had considered defecting to Britain's ruling Conservative party.

Woolfe, who serves as MEP for Northwest England, said he had been treated by doctors for seizures, partial paralysis and loss of feeling in his face and body.

He also confirmed that he had made a police complaint about the incident.

UKIP has been in crisis since its long-time leader Farage stepped down shortly after Britain's June 23 referendum result, which itself was not Farage's first attempt to step back from the leadership. He is currently back as acting leader after his replacement Diane James lasted barely two weeks in the post.

UKIP said on Monday it would pick its next leader on November 28.

mm/msh (AP, Reuters)