The announcement brings to seven the total number of troops killed across the region in the past day. Another 10 troops have been injured, according to the officials.
An AFP reporter in the rebel stronghold of Donetsk reported low-level bombardments around the airport early today although a local official later said this had increased in intensity.
The casualties come with the unrest in Ukraine high on the agenda at a G20 summit in Brisbane, where Western leaders are expected to put fresh pressure on Russian President Vladimir Putin.
Seven months of fighting in eastern Ukraine has claimed the lives of more than 4,000 people, according to figures from the United Nations.
A ceasefire agreed in September has stopped fighting along much of the frontline but not artillery bombardments around strategic hotspots.