A Ukrainian official says three soldiers have been killed in the past 24 hours in fighting in eastern Ukraine.

Military spokesman Andriy Lysenko told reporters on Wednesday that the situation remains tense and that pro-Russian rebels are attacking the army on all fronts.

The military conflict between Russia-backed separatists and the government forces in eastern Ukraine has been raging since April, claiming more than 5,100 lives, according to the United Nations.

Lysenko said the fighting is particularly fierce in Debaltseve, a strategic town which links the Donetsk rebels with the separatists in the Luhansk region.