Russian forces prevented two Ukrainian units from breaking out of an encirclement in the northern part of the Kharkov region, according to a source in Russian security structures.

The source said two combat groups from Ukraine’s 22nd Mechanized Brigade attempted to leave the encircled area near Chernoye on foot, but their movement was detected in advance by Russian reconnaissance.

Earlier in September, Russia’s Sever group of forces reportedly surrounded about 1,700 Ukrainian servicemen on the Kharkov sector.

Russian President Vladimir Putin said the encircled area covers roughly 460 square kilometers and includes 27 settlements. According to him, eliminating this pocket would push the line of contact at least 20 kilometers farther away from the border areas of the Belgorod region.

The Russian Defense Ministry also reported a day earlier that Russian troops were continuing to expand their zone of control in the Kharkov region.

According to the ministry, active fighting is underway near Podsredneye, Novoselovka, Petropavlovka and Prikolotnoye.

The ministry added that over the past 24 hours, Russian forces had eliminated up to 40 Ukrainian servicemen and one armored vehicle in this sector.