The Labour Party has suspended its Brighton and Hove branch amid claims of bullying and intimidation at its annual general meeting (AGM).
The election of a new executive committee (EC), which saw supporters of party leader Jeremy Corbyn voted into five top positions, was also annulled.
Labour's national executive committee said the suspension followed "alleged abusive behaviour" at Saturday's AGM.
New branch secretary Greg Hadfield said they were "fabricated smears".
A letter sent by Katherine Buckingham, the national party's head of disputes and discipline, said Labour had received "many complaints and reports of concern" following the meeting.
She wrote: "These allege abusive behaviour by some attendees, as well as reports that the ballot results were not properly reached.
"We are particularly concerned that the safety of members at the meeting was compromised."
The Brighton, Hove and District Labour Party will not be able to hold any meetings or leadership hustings until after the result of the national leadership election is known.
The letter states that any further meetings "may put the safety of members at risk".
Last weekend's vote was a distinct shift to the left for the branch, which has seen its membership treble in the past year.
More than 600 people attended the meeting at City College to vote in the senior members of the group following a rally by the pro-Corbyn grassroots group, Momentum.
Claire Wadey, who was one of the five people elected to the EC on Saturday, described the meeting as "incredibly tolerant, incredibly kind, very patient and respectful to all candidates".
"I really don't understand where this is coming from," she said.
Mr Hadfield said it was elected with more than 60% of votes cast, and it still intended to go ahead with its inaugural meeting next Tuesday.
He has asked for those who attended the AGM to "email their experiences" to the local party.