The attack, reported by the SDA news agency, was among the isolated cases of violence marring the 22nd annual techno parade, which attracted almost one million people on Saturday night, with partying continuing into the wee hours of Sunday.

The British victim was assaulted around 6.30pm in the Bürkliplatz but the assailant fled the scene.

No information about the man's condition was immediately available.

In another incident,  Zurich police arrested a 22-year-old woman after she head-butted an officer who was attempting to deal with her after attacked an employee in a restaurant.

City and cantonal police were out in force to maintain security at Switzerland’s largest street party, which features a parade with “lovemobile” floats accompanied by techno dance music.

With sunny skies and temperatures up to 25 degrees the parade attracted 950,000 people, similar to last year but short of the record attendance of around one million achieved in 2004 and 2005.

With this year’s motto, “Dance for Freedom”, the Street Parade officially calls itself a demonstration for love, peace, liberty, generosity and tolerance.

But as in past years some participants ignored the guidelines.

City police arrested 16 people aged between 17 and 33 mainly for assault and drug possession.

Zurich cantonal police said they arrested 28 men and one woman, mostly for drugs, drunkeness and “offences against the law on foreigners”.

Among the 29 arrested by cantonal police, 21 were from foreign countries.

Police said they worked with transport police to secure Zurich’s main train station until early Sunday morning to prevent potential problems for passengers.