The Ukrainian army said Russian-backed separatists targeted its positions with grenade launchers and mortars, wounding one serviceman.
Ukraine has said that one of its soldiers was killed in fighting with pro-Russia separatists in the east of the country.
The latest death on Friday brings Ukraine's toll in the simmering conflict to 65 since the start of the year, compared to a total of 50 in all of 2020.
The Ukrainian army said separatists had targeted its positions with grenade launchers and mortars.
"One serviceman was fatally wounded," and another soldier was injured, it said on Facebook.
Meanwhile, European Commission President Ursula von der Leyen said Brussels is ready to impose sanctions with a "massive cost" for Moscow if the Russian military invades Ukraine.
"Let there be no doubt. If Russia were to move against Ukraine, the Union will be in a position to take sanctions that could extract a massive cost. We have done our work in that respect," von der Leyen told in a news conference following a summit of EU leaders in Brussels.
US President Joe Biden also warned his Russian counterpart President Vladimir Putin of "sanctions like he's never seen" should the troops attack Ukraine.
Battling pro-Moscow separatists
Kiev has been battling a pro-Moscow insurgency in two breakaway regions bordering Russia since 2014, when the Kremlin annexed Ukraine’s Crimean peninsula.
Russia has massed around 100,000 troops on its side of the Ukraine's border.
The Western countries have accused it for weeks of planning an invasion, warning Moscow of sanctions should it launch an attack.
Kiev and its allies accuse Russia of supporting the rebels militarily - claims which Moscow denies.
The conflict in eastern Ukraine has so far left more than 13,000 dead.