At least 11 persons were killed in separate clashes between police and guerrillas in the northern Caucasus republics, according to reports on Sunday, according to DPA. At total of eight rebels died in the republics of Chechnya and Ingushetia, according to the Interfax news agency, while three policemen were killed in a Saturday ambush by extremists in the republic of Dagestan. Units of the Russian police and army have been battling underground rebels in the northern Caucasus for several years.