Ukraine’s army on Saturday reported the death of six soldiers in the past day of fighting against pro-Russian insurgents in the former Soviet nation’s separatist east.

Chief military spokesman Andriy Lysenko said 14 troops were also wounded in clashes across the rebel-controlled regions of the Donetsk and Lugansk provinces.

The single-day military toll is one of the heaviest reported in two weeks of sporadic fighting that has jeopardised the future of a February truce deal put together with the help of Germany and France.

At least seven people — five of them civilians — were reported killed on Thursday and more than 35 died last week in exchanges of mortar and rocket fire across the buffer zone established between the sides’ forces by the February accord.

The United Nations estimates the conflict in Ukraine has killed at least 6,400 people and driven more than a million from their homes.