A peace plan to end the conflict in eastern Ukraine came under renewed strain on Wednesday, with Ukraine and Russia clashing publicly over the next steps and further Ukrainian military casualties from rebel attacks testing a fragile ceasefire.
Moscow reacted sharply after Ukraine agreed on Tuesday to confer special status on rebel-controlled eastern regions and grant them limited self-rule - but only once local elections had been held under Ukrainian law, something unpalatable for rebel leaders who have proclaimed their own "people's republics".
Russian Foreign Minister Sergei Lavrov said the Ukrainian parliament had sought to "re-write" the agreement reached in Minsk, Belarus, last month. The Kremlin said the Minsk deal was now further away from being realised than it was a few days ago.
In Kiev, Prime Minister Arseny Yatseniuk responded that no one on the Ukrainian side had much optimism that Russia "and the terrorists" would readily fulfil the Minsk plan.
"First and foremost: to comply with the Minsk agreements, the Russian bandits must clear out of the territory of Ukraine and give the possibility to Ukraine of carrying out honest and transparent elections in line with international standards," he said in televised comments at a government meeting.
The dispute, which could lead the deal into a dead-end, highlighted the different strategies towards the issue of self-rule in the east.
Kiev is pushing a decentralization agenda in which it makes concessions aimed at blunting a drive for independence, while Moscow appears to be supporting a push by the rebels for powers that could give them veto over national policy and coming closer to officially recognizing the setting-up of the two "people's republics" in Ukraine's east.
The ceasefire struck at the summit of the leaders of Ukraine, Russia, Germany and France in Minsk came under pressure with the Kiev military saying one Ukrainian soldier had been killed in rebel attacks in the past 24 hours and five wounded.
Fighting in a conflict in which more than 6,000 people have been killed has greatly diminished, although huge areas of Ukraine's industrialized east, including the big cities of Donetsk and Luhansk, are under rebel control.
Heavy military equipment has been withdrawn to put the opposing sides out of range of each other's big guns in line with the agreement.
There is concern in Kiev that Mariupol, a port city of half a million on the Sea of Azov and which is still held by the government, could be a prime target for the Russian-backed rebels should the ceasefire collapse.
Comments by Ukrainian leaders suggest the pro-Western leadership of President Petro Poroshenko steamrollered the law through parliament, not through any real conviction it would be acceptable to the rebels, but to show the West - whose financial and political backing it relies on - it was abiding by the deal.
In Washington, the White House said President Barack Obama and German Chancellor Angela Merkel in a phone call reiterated their agreement that there will be no easing of sanctions on Russia over its support for Ukrainian separatists until it has fulfilled all of its commitments under the Minsk agreement.
The White House said U.S. Vice President Joe Biden, who spoke separately with Poroshenko, welcomed Ukraine's move regarding special status for the rebel-controlled eastern regions, the White House said.
Western governments, who are backing a $40 billion aid package for Ukraine over four years, regard the Minsk agreement as still the best opportunity for a lasting settlement.
Kremlin spokesman Dmitry Peskov said: "Judging by the last decision made by the Rada (Ukrainian parliament), we are today further from realising the Minsk agreements than we were a few days ago."