London's famous Notting Hill Carnival transformed the streets into a sea of colour and sound on Sunday as revellers joined one of Europe's largest open-air parties in their thousands despite heavy rain in the British capital.

The carnival featured steel bands, dance troupes and elaborate floats, with many among the crowds hurling paint and coloured powder at each other while dancing on the city's streets.

Police deployed metal-detecting arches to counter potential knife crime and have been additional stop-and-search powers at this year's carnival based on intelligence and after a spate of violent crime in London over the past week.

Established in 1966, carnival was set up to celebrate Afro-Caribbean culture, which flourished with immigration after World War Two. Confrontation with the far right followed, and race riots erupted in what was a shabby immigrant enclave in 1958.

Now the area is one of London's richest, lined with elegant stucco houses that are home to bankers, oligarchs and stars.

Despite the carnival attracting hundreds of thousands of people and putting the area on the tourist map, it also contributes an estimated $118 million (93 million pounds) to London's economy, according to the mayor's office.