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".
Pro-Russian separatists have agreed to start the withdrawal of heavy weapons in eastern Ukraine, a senior rebel commander has said.
"The plan was signed last night, starting from today there are two weeks to withdraw heavy weapons," Eduard Basurin was quoted as saying by Russian news agency Interfax.
It comes as government forces and separatists exchange dozens of prisoners as part of the internationally brokered ceasefire deal.
Yesterday, US Secretary of State John Kerry said the US and Europe were discussing potential further sanctions against Russia after several breaches of the truce were reported.
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.