Ukrainian officials say seven troops were killed in overnight fighting in the restive east.
The Ukrainian army has been fighting pro-Russian rebels in the east for weeks, and hostilities have continued despite President Petro Poroshenko's promise this week of an upcoming cease-fire.
Vladislav Seleznev, spokesman for Ukrainian forces in the east, said seven soldiers were killed and 30 injured in fighting outside the village of Yampil since yesterday. Seleznev said today that 300 rebels were killed, but that could not be immediately verified.
While NATO yesterday reported that Russia was resuming a military build-up at the Ukrainian border, Russian President Vladimir Putin has voiced concern about the Ukrainian military onslaught.
The UN says at least 356 people, including 257 civilians, have been killed since May 7 in eastern Ukraine.
