A group of pro-Russian demonstrators attacked the administrative headquarters of the Donetsk region in southeastern Ukraine, local media reported on Sunday.

The activists flew Russian flags over the building and put up posters of the Donetsk Republic separatist movement.

According to the local press, the administrative HQ is currently surrounded by hundreds of demonstrators and police have brought to the area at least one water cannon.

The takeover came after a pro-Russian demonstration in the region, which is the birthplace of deposed Ukrainian President Victor Yanukovych.

According to some witnesses, local police bowed to the demands of the activists, allowing them to take over the building in an orderly manner.

Simultaneously, according to several reports in the Ukrainian press, in the eastern city of Luhansk a group of pro-Russian activists burst into the Ukrainian Security Service's HQ.

The activists are demanding the release of a companion, activist Alexander Kharitonov, who was arrested for participating in protests against the new Ukrainian authorities.

In addition, in the northeastern city of Kharkiv, clashes were registered between local sympathizers with the new authorities and pro-Russian forces.

This is not the first time that pro-Russian activists have attacked the headquarters of state institutions in Donetsk and other cities in eastern and southeastern Ukraine, where there is strong pro-Russian feeling. As a result, Ukrainian authorities are apprehensive about the possibility of a repeat of the separatist activity that ultimately led to Russia's annexation of the Crimea.

The annexation was approved in a referendum held in Crimea on March 16 using the argument that the majority Russian population there was being threatened by radical ultranationalist Ukrainian forces. EFE