Russia dismissed on Thursday calls from Kiev for UN peacekeepers to be deployed in east Ukraine, saying the basis for a resolution of the conflict with pro-Russian rebels there should be the Minsk agreements signed this month.
Russian Foreign Ministry spokesman Alexander Lukashevich also said that responsibility to implement the Feb. 12 Minsk agreements lay with Kiev.
Ukrainian President Petro Poroshenko had called for United Nations peacekeepers to be deployed to monitor a cease-fire in east Ukraine, a proposal that pro-Russia rebels swiftly said would be in breach of the peace deal.
At an emergency meeting late Wednesday, Ukraine's national security and defense council approved Poroshenko's request, a clear sign of Ukraine's concerns after pro-Russian rebels seized a key town after the cease-fire took effect on Sunday.
"The best format for us is a police mission of the EU," Poroshenko said, according to a statement on his website. "It will be the most effective guarantor of security in the situation when the word of peace is not observed either by Russia or by those who are supported by it."
In response, Lukashevich said the way forward had been set out in last week's deal. "The basis for forthcoming work on a final resolution to the Ukraine [crisis] should be the concept laid out in the Minsk accords of Feb. 12," he said.
Poroshenko, who accuses Moscow of sending troops and weapons to fight Ukrainian troops, said Russia could not take part in the peacekeeping mission as it was an "aggressor country."
Deputy Secretary General of the EU's diplomatic service Maciej Popowski said Brussels needed clarity on the mandate, which would then need to be discussed with member states.
"Our priority is now to support the implementation of the Minsk agreement. And this is already ongoing," he said.
"There are EU civilian advisers in Ukraine, the EU advisory mission, but working on institution-building, the reform of the ministry of interior and police."
Ukraine pulled thousands of troops out of the east Ukrainian town of Debaltseve on Wednesday after failing to stop an offensive by Moscow-backed rebels who said the railway hub was not part of the cease-fire.
The rebels denounced Poroshenko's call for peacekeepers, saying their presence would violate the cease-fire, negotiated in marathon talks by France, Germany, Russia and Ukraine in the Belarussian capital Minsk.
"This is an actual violation of the package of measures to implement the Minsk agreement," Denis Pushilin, a senior separatist figure, was quoted as saying by Russia's RIA Novosti news agency.
"And so we have a very negative attitude to this. Moreover we are ready to address the heads of state who were guarantors that Ukraine would meet its commitments."
Russia's ambassador to the United Nations was also quoted as saying that Poroshenko's proposal put into doubt Ukraine's resolve to fulfill the Minsk agreements.