A McDonald's restaurant was wrecked as the protest against global capitalism turned ugly this afternoon.
Three police officer were injured and at least one was taken to hospital after he was struck in the face by a brick thrown by a protester.
Officers stopped protesters from leaving Traffalgar Square and the atmosphere was reported as being tense as protesters were tried to leave.
More than 2,000 eco-activisits had packed into Parliament Square, but there was little trouble in the May Day sunshine during a "Guerrilla Gardening" event organised by militant pressure group Reclaim the Streets to symbolise the reclaiming of urban spaces.
Groups dug up turf and dug a pond while others planted seeds.
There were at least seven arrests. Some were for possession of weapons, but the first sign of major problems came as protesters let down tyres of cars trapped in the traffic gridlock caused by road closures surrounding the protest.
Then, at about 2.10pm a group of 20 protesters stormed into the Whitehall branch of McDonald's and destroyed the restaurant.
Within minutes the group had smashed every single window and torn down the 'M' sign outside the restaurant.
The group also sprayed graffiti over the property as riot police armed with shields and truncheons sealed off the area. Protesters were filmed handing out drinks and burgers inside the restaurant and TV crews were attacked.
The protest was part of a World-wide anti-capitalism demo which saw violent outbursts in Germany, Poland and the USA.Reuse content