Four Ukrainian servicemen have been killed and 15 wounded in fighting with pro-Russian rebels in the past 24 hours just before talks on a ceasefire were due to start, the Ukrainian military said on Monday.
Casualties reported before peace talks
They also accused Ukrainian troops of firing heavy weapons.
It was the highest casualty figure in over two weeks.
Ukrainian military spokesman Andriy Lysenko said separatists were firing heavy weapons banned under a peace agreement and described the situation in western districts of rebel-held Donetsk as the most tense.
There "fighting with occasional tank and artillery fire goes on round-the-clock," he said in a daily military briefing.
Representatives of Ukraine, Russia and rebels prepared to meet in Minsk, Belarus, on Monday for further talks on implementing the much-violated ceasefire deal agreed in February.
Twenty-nine Ukrainian servicemen were killed and 175 wounded in separatist eastern territories in July despite the ceasefire, according to a Reuters tally.
On Monday, rebel officials said 22 civilians and rebel fighters and been killed and 29 wounded last month as a result of attacks from the Ukrainian side, separatist press service DAN reported.
The meeting in Minsk of the so-called "contact group" involving Ukraine, Russia and the separatists under the auspices of the Organization for Security and Cooperation in Europe was expected to address extending the pull-back of weapons to include tanks and smaller weapons systems.
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