The clash occurred when the opposition Congress activists forced entry into the office of the district collector after breaking the security cordon. The activists were demanding arrest of the prime accused involved in killing of a local party leader, police said.
Former chairman of Bhapur block, Gurubari Kanhra was allegedly killed by a group of miscreants on June 13. Though police have booked some persons in the Gurubari killing case, the party leaders demanded arrest of the prime accused.
While the security personnel were injured due to stone pelting by Congress activists, others sustained injuries as police resorted to mild lathicharge, sources said.
"The police resorted to mild lathicharge to chase away the agitating youths," Nayagarh superintendent of police (SP) Sesadev Mallick said.
Rejecting the allegation of police protecting the miscreants involved in the Gurubari murder case, the SP said the police have already arrested four persons in this connection. "More arrests will be made soon," the SP said.