Ukraine's military says one of its soldiers has been killed and another wounded in fighting in eastern Ukraine over the past 24 hours.
The casualties underscore the fragility of a cease-fire between government forces and Russian-backed separatists in a conflict that has killed more than 6,000 people since April.
Zoryan Shkiryak, an adviser to Ukrainian Interior Minister Arsen Avakov, accused the rebels on March 5 of violating the truce agreement signed in Minsk last month and of building up forces near the government-held coastal city of Mariupol, on the Azov Sea.
Meanwhile, rebel officials said no shelling or fighting was reported in Donetsk region overnight.
In the Black Sea port city of Odesa, police are investigating an overnight explosion outside the office of the nationalist group Right Sector.
No casualties were reported.