KIEV, June 20 - Around 4,500 members of illegal armed groups are active in the southeastern regions of Ukraine, said Valentyn Nalyvaichenko head of the Ukrainian Security Service.

"We are aware of the background, numbers and location of Russian officers, saboteurs, mercenaries and traitors from police and SBU… Such groups of terrorists and gunmen in Donbas include a total of 4,500 people," he said in an interview with the Den daily published on Friday.