Far-left protesters in motorcycle helmets clashed with riot police outside La Scala in Milan last night, bringing an element of class war to a glittering gala.

Before the first night of Beethoven’s Fidelio, up to 1,000 policemen were employed to protect the audience. La Scala, an exclusive social club for Milan’s aristocracy and captains of industry, has always invited the opprobrium of left-wing activists. With the risk of violence this year fuelled by controversial labour reforms and surging unemployment in the city, the authorities took the unusual step of closing roads around the theatre.

Shortly before the performance began at 6pm, protesters threw gas canisters and eggs, before being pushed back with a baton charge by riot police. At least two protesters needed treatment for head injuries.

Class war in Milan: Anti-government activists clash with police Show all 7 1 /7 Class war in Milan: Anti-government activists clash with police Class war in Milan: Anti-government activists clash with police Italy A demonstrator holds a flare during a protest in front of La Scala opera house on the first day of opera season in downtown Milan Class war in Milan: Anti-government activists clash with police Italy Police fight with demonstrators during a protest in front of La Scala opera house on the first day of opera season in downtown Milan. As with previous years, demonstrations would take place on opening night as a way of highlighting protesters' demands and various issues in the country Class war in Milan: Anti-government activists clash with police Italy Riot police and protesters clash during a protest against the Italian government prior the premiere of Ludwig van Beethoven's opera 'Fidelio' as the Teatro alla Scala kicks off its season in Milan EPA Class war in Milan: Anti-government activists clash with police Italy Riot police and protesters clash during a protest against the Italian government Class war in Milan: Anti-government activists clash with police Italy A demonstrator holds a flare during a protest in front of La Scala opera house. The placard reads, "Stop with empty houses" Class war in Milan: Anti-government activists clash with police Italy Cub activists and members of social centres protest clash with police outside the Scala opera house Class war in Milan: Anti-government activists clash with police Italy Cub activists and members of social centres protest outside the Scala opera house

Christine Lagarde of the IMF, Italy’s Culture Minister Dario Franceschini, and senate president Pietro Grasso were among the guests.

Far-left and anarchist groups had been making threatening comments in the run-up to the opening night, with “See you on 7/12” sprayed on walls after a series of recent evictions from Milan social centres such as Zam and Rosa Nera.

One of the flyers doing the rounds in the past few days said: “Masters and rulers will be at the Scala to celebrate the riches accumulated at our expense over a year: a display of limousines, Rolexes and fur coats.”

With tickets for the gala night – one of the top events in the social calendar – changing hands for thousands of euros, it is an event for the very few.