Three Ukrainian soldiers have been killed in the past 24 hours in fighting in eastern Ukraine, officials say.
Military spokesman Andriy Lysenko said the situation remains tense and pro-Russian rebels are attacking the army on all fronts.
The conflict between Russian-backed separatists and government forces in eastern Ukraine has been raging since April, claiming more than 5,100 lives, according to the United Nations.
Mr Lysenko said the fighting is particularly fierce in Debaltseve, a strategic town which links the Donetsk rebels with separatists in the Luhansk region.