Scuffles have broken out outside Italy's La Scala opera house in Milan during a protest against labour market reforms and austerity measures.
The disturbances took place as Daniel Barenboim celebrated his last gala season opener as music director of La Scala on Sunday.
He brought the orchestra on stage to bask in a prolonged standing ovation.
La Scala's opening performance, which this year was Beethoven's Fidelio, is a highlight of Italy's cultural year.
It is often attended by top sportsmen, politicians and businessmen, although this year Italian Prime Minister Matteo Renzi and President Giorgio Napolitano stayed away.
As the performance began, protesters a few streets away threw flares, eggs and vegetables at riot police, who prevented them from getting too close to the 18th century theatre.
Wealthy guests - some paying as much 2,000 euros ($2,460) for a ticket - were jeered as they entered the building.
The protesters were upset about changes to labour laws which make it easier to dismiss workers.
Two police officers were reported to have been injured by flares and petrol bombs thrown by the protesters.
Argentinean-born Israeli conductor Mr Barenboim will leave La Scala at the end of this year.
Correspondents say that Italy's economic downturn has hit finances of the country's best known opera house.