NEW : At least 253 people protested peacefully . NEW Blair told reporters that packs of disruptive demonstrators infiltrated peaceful protests in order to cause chaos and distract police . : Canadian PM : We suspect group of thugs . Protests erupt in Toronto as G-20 leaders meet . Police have arrested more than 600 protesters since mid - June .
NEW : At least 253 people protested peacefully . NEW : Canadian PM : We suspect group of thugs . Protests erupt in Toronto as G-20 leaders meet . Police have arrested more than 600 protesters since mid - June .