Fifty dancers from the Paris Opera Ballet astounded museum-goers Sunday when they suddenly emerged from the crowd under the Louvre's glass pyramid entrance and started strutting their stuff.

They danced to the music of Johann Strauss's "Blue Danube" before being joined by 200 people who had earlier signed up to the "flashmob" performance, and jiving to the sounds of pop groups Queen and Daft Punk.

After just three minutes the dancers melted back into the crowd after leaving behind them dozens of pairs of ballet shoes marked with the web address of a children's charity for which the event was organised.

The charity called La Chaine de l'Espoir (The chain of hope) provides medical care for poor children in developing countries.