"The whole world is watching", this was the battle cry of the 200 anti-Olympic protesters who marched through downtown Vancouver on the first day of the 2010 Vancouver Winter Olympic Games on Saturday.

200 anti-Olympic protesters?marched through downtown Vancouver on the first day of the 2010 Vancouver Winter Olympic Games on Saturday.

What was supposed to be a peaceful protest turned into violence when masked protesters dressed in black damaged private property, spray-painting cars, breaking windows and throwing mailboxes onto the streets.

Riot police in bright yellow vests, some carrying tear gas canisters and what looked like machine guns, formed a barrier near Stanley Park.

City traffic came to a standstill as police vehicles descended on the area, and an army helicopter flew overhead at one stage.

Media were told that both the IOC and the games organizers VANOC support non-violent protest.

"Where we draw the line and where I suspect Canadians draw the line is when people get violent," Mark Adams of the IOC told this morning's daily briefing.