Aslef's general secretary Shaun Brady has been suspended

The alleged incident involved general secretary Shaun Brady, assistant general secretary Mick Blackburn and president Martin Samways.

It is claimed a party at the union's Hampstead headquarters on 20 May ended in a fight.

Mr Brady says he is angry at the union executive's suspension decision.

A spokesman for the TUC said its general secretary was going to offer the 17,000 train drivers' union help in the wake of the latest dispute.

"In the light of recent events in Aslef, TUC general secretary Brendan Barber is in contact with the union and will be meeting officers shortly to see what assistance the TUC may be able to provide in resolving the current internal difficulties," the spokesman said.

I have been the democratically-elected general secretary for eight months. It has been eight months of absolute hell Shaun Brady, suspended Aslef general secretary

Mr Brady, 41, elected to his post last July, is seen as a Blairite and has clashed with members of the more left-wing executive committee, of which Mr Samways, 57, is a member.

He has complained of losing day-to-day control of the union because of arguments with the executive and his concerns have led to an investigation of the union's finances over the past decade.

Mr Brady spoke of his frustration outside the Aslef offices shortly after the decision to suspend him.

"I have been the democratically-elected general secretary for eight months. It has been eight months of absolute hell," he said.

'Serious misconduct'

"This is not a battle between left and right - it is a battle between right and wrong. I call on the membership to get up and start fighting for the union.

"I was elected by the biggest majority ever known and I have been suspended against the wishes of my membership."

Mr Blackburn said he understood that there would be a police inquiry and that he would be interviewed.

Ahead of the announcement of the suspensions, Aslef spokesman Andrew Pakes told BBC News Online there had been an "altercation" at the barbecue.

WHAT IS ASLEF? Aslef is the principal trade union for train drivers It was founded in 1880 for drivers and train crew It has about 17,000 members working on trains, London Underground and trams Aslef is affiliated to the Trades Union Congress and Labour Party

"The EC [executive committee] were asked to consider it because a number of complaints were received.

"The complaints, made by several members of staff, alleged that the president hit a female member of staff."

He had said the general secretary's involvement in the incident would also form part of the discussion.

"The only complaints we received were those alleging the serious misconduct of the president," said Mr Pakes.

"This is regarded as a serious complaint, and rightly so - a member of staff has been hit quite badly and is still off sick.

"The vice-president of the EC will steer the process from here and the EC will decide the outcome."