In the past few days, Russian-backed militants have been most active over the last month, the ATO press center said.
"The most complicated situation is still near Donetsk. Militants have been shelling the villages of Pisky, Vodiane, Opytne, and the towns of Maryinka and Krasnohorivka since the very morning," the source said.
They have used almost all available weapons, including 120mm-caliber mortars and 122mm-caliber howitzers banned by the Minsk peace agreement.
What is more, the enemy used tanks, guns of combat vehicles and 122mm-caliber artillery systems to fire on facilities in the village of Opytne five times. They also hit and destroyed residential areas in the village of Vodiane.
"After a short break, the area around the Ukrainian-controlled city of Mariupol has again become a hot spot: ATO forces in the village of Shyrokyne were attacked eight times by militants, who used mortars and howitzers whose caliber is over 100 mm, as well as grenade launchers, heavy machine guns and small arms.
The town of Schastia and the villages of Krymske and Bolotne in Luhansk region were under 120mm mortar fire.
At the same time, the ATO press center said, the ATO forces have been beefing up their combat strength to be able to repel possible breakthrough battles and land grabs.