Ukrainian soldiers on Sunday captured two Russian servicemen in the country's separatist eastern areas.
"Two Russian servicemen are under arrest - our investigators are working with them," Kyiv military spokesman Andriy Lysenko said in a news conference. The Ukrainian army claimed it had captured the two Russian troops around 15 kilometers away from Luhansk, a rebel stronghold.
Three Ukrainian soldiers were killed and 17 wounded in a mortar attack near Svitlodarsk, northeast of the separatist-controlled city of Donetsk.
The pro-Russian separatists meanwhile accused Ukrainian troops of heavy firing near Donetsk airport on Sunday, killing one rebel leader and wounding another, rebel commander Eduard Basurin said in a statement to the rebel news service DAN.
Violence has considerably decreased in eastern Ukraine since a ceasefire deal was signed between Kyiv and the rebels in February. However, sporadic incidents of fighting still take place and often result in casualties.
Ukraine, European Union countries and the United States have accused Moscow of supporting the rebels and providing them with heavy artillery and weapons. NATO's top military commander, General Philip Breedlove, told the US Congress last month that Russia's military could be using the ceasefire to prepare a new offensive by eastern Ukraine's rebels.
Russia has denied the charges.
mg/sms (AFP, Reuters)