Ukraine says pro-Russian rebels have killed four of its soldiers and injured 15 in the past 24 hours.
The escalation came just hours before the latest round of talks on ending the conflict. The heaviest shelling was reported near rebel-held Donetsk.
BBC: Ukraine rebels kill four troops in heavier shelling
Ukrainian servicemen man a position held by Ukrainian forces on the front line at the village of Zaytseve in the Donetsk Oblast on July 29, 2015.
