By Ollie Stone-Lee BBC News, TUC conference in Brighton

Livingstone opposed private firms running the Tube infrastructure

"Scab" is about the worst insult you can hurl at somebody who has spent a lifetime making a virtue of being on the left of politics.

And yet London Mayor Ken Livingstone cheerfully waved - and seemed even to blow a kiss - at Tube workers shouting the abuse at him in Brighton.

The demonstration was over plans to allow a private firm to run trains on a London Underground line.

The Rail Maritime and Transport union protest came at the TUC conference.

About 30 union activists, including general secretary Bob Crow, gathered outside Brighton's Grand Hotel as Mr Livingstone arrived to host his conference reception.

The unions say plans for the East London Line are a form of privatisation.

Transport for London disagrees, saying it will control the new franchise and will retain the revenue.

'Be ashamed'

The line will be part of London Overground which will form an orbital rail route round the city.

There were chants of "scab" as the mayor walked into the hotel. Earlier, Mr Crow shouted at one of the mayor's aides: "You should be ashamed of yourself."

The union leader told BBC News he was disappointed in Mr Livingstone, who is usually seen as a man of the left.

Livingstone said the East London line would benefit

"We are protesting because he is basically going down the same route as the Tories did - privatising the London Underground," said Mr Crow.

"He stood on a platform with me five years ago opposing the privatisation of the Tube infrastructure.

"I am disappointed. I never thought he would do this after the stand he took.".

Mr Livingstone told the conference fringe meeting the changes on the East London line would treble the number of trains.

And Transport for London would still set fare and staffing levels and working conditions.

He predicted that after a year or so the unions would be demanding he take over other lines and run them in the same way.

BNP pledge

Mr Livingstone also used his fringe speech to promise to take on the far-right BNP when he runs for re-election in 2008.

"To those people who say ignore them, I say that will not be the case," he said.

The mayor criticised people who said multi-culturalism had failed - an implicit attack on Trevor Phillips, who has just been appointed head of the newly created Commission on Equality and Human Rights.