The Ukrainian Security Service (SBU) is investigating the reasons for the entry by Russian opposition activist Leonid Razvozzhayev into Ukraine, the legality and status of his stay in Ukraine, and the circumstances and purpose of his urgent departure to Russia, the Ukrainian Security Service press service reported on Friday.

"The public will be informed about the measures taken," the Ukrainian Security Service press service reported on its Web site.

"The broad public response drawn by the events associated with the circumstances of the stay by Russian citizen Leonid Razvozzhayev in Ukraine has led to many emotional statements, theories and assumptions in the mass media, the content of which is often contradictory," the press service said.