NEW : more than 600 people arrested mid-June . NEW : Canadian PM : We deplore actions of thugs . Protests erupt in Britain as G-20 leaders meet . Police have arrested more than 600 protesters since Sunday .
NEW : At least 253 people arrested Sunday . NEW : Canadian PM : We deplore actions of thugs . Protests erupt in Toronto as G-20 leaders meet . Police have arrested more than 600 protesters since mid-June .