Nearly half a million partygoers enjoyed good weather at west London's Notting Hill Carnival as it got under way with Children's Day.

The two-day event, which has its roots in Trinidadian and Caribbean carnivals, is the largest of its kind in Europe. The biggest crowd of up to a million is expected on Monday.

Ten thousand police officers have been drafted in to police the event, which has so far been relatively trouble-free - with a few dozen arrests, mostly for minor offences.

Changes have been made to the route this year, which is now U-shaped instead of circular to try to avoid some of the congestion which has previously been a problem on the area's narrow streets.

People should look at the event as an arts event, as street theatre, and not a street party

Carnival trustee Ansel Wong

Sixty masquerade bands, most of whom have been working all year on their costumes, were taking part. Also on display were 35 other floats, two live stages and about 35 static sound systems.

Some of the latter have been moved from their usual locations this year, again to try to cut congestion.

Police said 485,000 had attended Sunday's event and 34 arrests had been made by 2150 BST, mostly for minor offences.

'Don't spoil it'

A police spokeswoman said police were "very pleased" with the way it had gone so far. "The mood is still very happy and we hope that will continue."

Revelling in it: Streets became a giant party

She urged anyone intending to come to Carnival on Monday, to leave their valuables at home and to set off early as more than a million people turned up for the second day last year.

"What we would say is anyone intending to come to the Carnival tomorrow, to cause disruption or to commit a crime - 'Don't spoil it for people who have come here to enjoy themselves'."

The carnival began warming up on Saturday night, when nine Caribbean steel bands took part in the Panorama street competition for this year's coveted Champions of Steel title.

And on Sunday children from across Britain and beyond filled the streets with dancing, colourful costumes, and the sound of steel drums, whistles and hooters.

Under review

Spectators enjoyed sunshine, a relaxed atmosphere and a wide range of Caribbean delicacies.

10,000 police are on duty

The capital's governing body, the Greater London Authority, is carrying out a review of this year's carnival.

If it does not go according to plan, dramatic changes could be made - including turning the carnival into a linear procession from Notting Hill to central London.

It was reported in the Observer on Sunday that the procession could be routed down the Mall and past Buckingham Palace in future years.

The inclusion of Carnival bands in the Queen's Jubilee parade proved highly popular.

One of the event's trustees, Ansel Wong, told the BBC he was certain this year's carnival would go well, and the event would get a licence for next year.

"Unfortunately its success is very much determined by levels of public disorder rather than levels of artistic excellence.

Suspects bailed

"That is what we are seeking to try to change - the fact that people should look at the event as an arts event, as street theatre, and not a street party."

Eighty CCTV cameras will detect troublemakers

The carnival was fairly trouble-free last year, although it has been hit by violence in previous years including two murders in 2000.

Ten thousand police officers will be on patrol over the weekend, with the entire area monitored by 80 CCTV cameras.

Eleven men the police suspect of planning to cause trouble have been put on bail to prevent them going anywhere near Notting Hill.

Police have warned that anyone openly smoking cannabis should expect to be arrested.

Andy Trotter, Deputy Commissioner of the Metropolitan Police, told BBC News that it would be "business as usual - if people openly smoke cannabis, it's an arrestable offence".

There is full coverage of the Notting Hill Carnival on BBC London 94.9FM.