Close to half a million people swamped Zurich for the annual techno music Street Parade on Saturday, Europe's second-largest techno festival after the Berlin Love Parade.

Techno fans, called ravers, garbed in flashy costumes or scantily clad for the hot weather, swarmed from across Europe for the parade of 30 booming sound trucks along the city's lakefront."The atmosphere is relaxed and peaceful," said a spokesman for the parade organizers in Zurich, Switzerland's largest city of 1 million.

Swiss railway SBB ran 50 extra trains into Zurich from all points and estimated that 200,000 people came by train especially for the parade.

Around 900 police and medical officers were on duty, but the only problems reported were minor injuries such as cuts.

Some ravers were affected by the heat after dancing and standing in the afternoon sunshine when temperatures reached 86.

After the parade, ravers had a choice of 40 all-night techno parties located across the city, including Zurich's biggest sports stadium and a forest clearing above the city.

Techno music is a mix of thundering beats and repetitive electronic bleats spun by disc jockeys using massive sound systems.

Zurich's Street Parade started in 1992 and has grown from around 2,000 dedicated ravers the first year to a mix of dancers and spectators that last year also attracted 500,000 people.

Berlin's Love Parade on July 11 drew close to 1 million people.