Up to 6,000 career servicemen of the Russian Armed Forces are currently present in temporarily occupied Donetsk and Luhansk regions, Ukrainian Security Service (SBU) Chief Vasyl Hrytsak has said.

"I believe, and this is my position, that Russia is a party to this conflict. It does not acknowledge this, but how else can we explain the presence of 4,000 to 6,000 Russian servicemen in our territory?" Hrytsak said at a press briefing in Odesa on Friday.

Ukraine has repeatedly provided evidence of the presence of Russian servicemen in its territory, in particular, to international partners, he said.

"These are Russian career servicemen," Hrytsak said.