Striking arts workers have taken to the streets of Paris

The strike, which started on Monday, will now continue until at least Wednesday night. It is centred on government plans to change arts workers' unemployment benefits.

The Avignon festival was due to start on Tuesday with a piece of "equestrian theatre" by the French troupe Zingaro and a ballet drama to the music of Mozart by Belgian director Alan Platel.

Another meeting will be held on Wednesday by festival organisers as a last-ditch attempt to save it.

"We call on all professionals to continue the strike action and make the strike widespread," said Jean Voirin, the secretary general of the CGT union's arts division, after talks in Paris ended.

"This text is treacherous, we will fight it as long as it takes."

Avignon fears a loss in tourism revenue if the festival fails

Other unions had signed a codicil, or additional agreement, which supported an offer by Culture Minister Jean-Jacques Aillagon to postpone the new system until next year.

Other arts venues, such as the Paris Opera and the lyrical arts festival in Aix-en-Provence, cancelled performances, while at least 6,000 art workers took to the streets of Paris to protest over the government's plans.

Other demonstrations took place in Avignon and La Rochelle, and another group managed to disrupt the Tour de France cycle race.

Avignon's festival is one of the most prestigious in Europe, drawing in about 100,000 people each year, and generating more than 15m euros (�10.4m) in revenue. The festival lasts 20 days.

Performers in Avignon on Monday evening

At present, unemployment benefit is given to everyone who works in the arts - including buskers and comedians.

Currently, if they work 507 hours a year, they can claim benefit for the rest.

The government said there is too much scope for abuse - but the strikers say the new rules are an attempt to ruin the arts.

Under the new plans, artists will have to work for 507 hours during 10 and a half months to earn eight months' worth of benefits.

A dance festival in Montpellier, which usually draws 30,000 fans, has been called off while events in Marseille, Pau and Rennes have also been cancelled.