Fighters of the Ukrainian National Guard have arrived at the state border in the Donetsk region, spokesman for the National Security and Defense Council Volodymyr Chepovy announced.

"At the Ukrainian president's instruction to regain control over the state border, units of the National Guard were deployed on June 16 at the state border and in populated areas of Donetsk region," he said at a press briefing on Tuesday.

National Guard fighters have assumed duty at checkpoints and in reserve groups intended to react to emergencies, he said.

Chepovy said that a series of successful operations has been conducted over the past 24 hours to regain control over the state border and "to destroy members of criminal armed formations in Donetsk and Luhansk regions."

"Following a series of operations the surviving terrorists and members of subversive groups retreated to new bases and strongholds," Chepovy said.

"About 80 militants have been neutralized over the past 24 hours in the counterterrorism operation," he said.