Russian foreign minister Sergei Lavrov called on Ukraine to distance itself from what he called "extremists" in the east and pursue a course towards peace. He said "tangible progress" had been achieved in implementing measures agreed in Minsk this month and that the ceasefire was being "consolidated".
Ukrainian military and separatist representatives have exchanged dozens of prisoners at a remote frontline location, kicking off a process intended to usher in peace to the conflict-ridden east.
The prisoner swap saw 139 Ukrainian troops and 52 rebels exchanged at a no man's land location near the village of Zholobok, some 12 miles west of the rebel-held city Luhansk.
A busload of Ukrainian soldiers in military fatigues was transported earlier in the day from the main rebel stronghold of Donetsk to a rural spot some 90 miles to the north-east, before joining up with other groups of fellow captives.
The peace agreement signed last week in Minsk foresees an exchange of all prisoners in the conflict.
It is unclear how many are held in total on both sides, although the Donetsk separatists have said Ukraine is holding about 580 rebels as prisoners.
Thousands of Russians are marching in Moscow to mark the first anniversary of what they viewed as a "coup" in neighbouring Ukraine.
14 soldiers died and many more were injured as Ukraine left the strategically important hub of Debaltseve.
Dramatic footage shows the moment a TV crew were forced to flee a huge explosion after a gas pipeline was hit by mortar fire in Ukraine.