Three protesters in Montebello, Canada during the Security and Prosperity Partnership of North America were caught acting as police provocateurs on August 20, 2007, by Dave Coles, president of the Communications, Energy and Paperworkers Union of Canada. The entire incident was filmed and posted on YouTube before being picked up by mainstream media. The video [4] shows three masked men, one of whom was armed with a large rock, being confronted by peaceful protesters. After the men breached the police line, they were brought to the ground, handcuffed, and taken away. Photographs revealed that their boot-tread matched that of the arresting officers. Although they at first denied that the individuals in question were agents provocateurs, the Sûreté du Québec issued a news release on August 23 admitting that the three protesters were, in fact, police officers

http://en.wikipedia.org/wiki/Agent_provocateur