Britain's UK Independence Party, whose growing influence helped prompt the referendum that saw the country vote to quit the European Union, has been plunged into turmoil over the choice of a new leader.
Nigel Farage, among Britain's most outspoken and effective anti-EU campaigners, stood down as party leader last month after realising his ambition of winning the referendum.
On Wednesday, the party's National Executive Committee (NEC) said Steven Woolfe, the favourite to replace him, had been excluded from the leadership ballot after submitting his nomination papers late.
The decision is likely to lead to civil war over the future of the party, fuelling tensions between those loyal to Farage and those, including UKIP's only MP Douglas Carswell, who want to take UKIP in a more liberal direction.
On Sunday, a spokesman for Woolfe said he had submitted his application before the deadline but due to "technical problems" it had gone through 17 minutes too late.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
"By a clear majority of NEC members, Steven Woolfe MEP's application was considered to be ineligible as a result of a late submission," the party's returning officer Adam Richardson said in a statement.
It was in a bid to stave off rising support for UKIP that former prime minister David Cameron first promised the EU referendum in 2013, and the party and its large grassroots network played a key role in the campaign to leave the bloc.
UKIP won 12.6 per cent of the vote at last year's national election but due to Britain's winner-takes-all system, only has one seat in parliament.
Woolfe, the party's spokesman on migration and financial affairs, said he was disappointed by the decision.
"Over the course of this leadership election, the NEC has proven it is not fit for purpose and it confirmed many members' fears that it is neither effective nor professional in the way it governs the party," he said.
"They have failed to accept that there were serious issues with the application system despite providing evidence that attempts of submission were made before the deadline."
