Yesterday pro-Moscow rebels fired at government positions south of Avdiivka, an industrial town located just north of rebel hub Donetsk, the Ukrainian military said in a statement on Facebook.
"The bandits didn't stop at their regular provocations and fired at our positions using barrel-mounted and automatic grenade launchers," it said.
"One soldier was killed and two were injured," it said.
Kiev and the separatists signed a truce which came into force on September 1.
The army reported two fatalities on September 14, and the rebels said they lost a fighter last weekend on the outskirts of Donetsk.
Ukrainian President Petro Poroshenko said last week that he thought the war was still not over but a "real truce" had finally begun.