Several thousands of Ukrainian troops remain encircled by pro-independence forces in Debaltseve, one of Ukraine's biggest railroad junctions.
"Today, despite our efforts and the efforts of the OSCE mission, they were not allowed to enter Debaltseve… This is a direct violation of the obligations and the spirit of the Minsk agreements, as the mission is the only mechanism for monitoring the ceasefire," Klimkin said at a press briefing.
Earlier on Sunday, at midnight in Ukraine (February 14, 22:00 GMT) a ceasefire deal between government forces and independence supporters in Donbas became effective.
The truce was hammered out by the leaders of Russia, Ukraine, France and Germany earlier this week during the talks in Minsk.
The agreement stipulates that the OSCE must conduct a thorough monitoring of the ceasefire. The organization's Special Monitoring Mission has been reporting on the situation in Ukraine since March 2014.
