Participants of the rally attack an unidentified man (R, front), treated as a provocateur by the rally organizers, in front of the Kiev City State Administration (Kiev City Council) building during a rally held by supporters of EU integration in Kiev, December 1, 2013. Ukraine's interior minister warned tens of thousands of protesters starting a pro-Europe rally in the capital Kiev on Sunday that police would respond if there were mass disturbances. [Photo/Agencies]