Ukraine's president has called for new sanctions against Russia over its decision to recognise passports issued by separatist authorities in the east.
Petro Poroshenko denounced Moscow's action as contradicting the 2015 peace agreement.
Speaking at a meeting with EU humanitarian aid and crisis management commissioner Christos Stylianides, Mr Poroshenko called for "resolute action, up to strengthening sanctions".
The Kremlin accused Ukrainian authorities of denying vital documents to people in the rebel regions.
Officials said the decision was a "humanitarian" move to help residents of the east suffering from Ukraine's blockade, and does not amount to recognising rebel regions.
Ukrainian forces have been fighting Russia-backed separatists in eastern Ukraine since April 2014 in a conflict that has killed more than 9,800 people.
The US and the European Union have hit Russia with sanctions for its annexation of Ukraine's Crimean peninsula and support for pro-Russian insurgents in eastern Ukraine.
The February 2015 peace agreement brokered by France and Germany has helped reduce fighting in the east, but clashes have continued and provisions for a political settlement have stalled.
Russia and Ukraine have blamed each other for the lack of progress.
Russian foreign minister Sergey Lavrov said the decision to recognise passports and other documents issued by separatist authorities in the east was intended to protect the rights of local residents, who have found it impossible to receive documents from Ukraine because of its blockade.
"The Ukrainian authorities are doing all they can to make life as difficult as possible for the residents of those territories and make it as hard as possible for them to enjoy the most basic rights and freedoms," Mr Lavrov said.
"It's hard and often impossible to exercise those rights without documents."
Meanwhile, Montenegro's former prime minister has accused Russia of "destructive" politics in the Balkans following what the country says was a thwarted attempt to overthrow its pro-Western government.
Milo Djukanovic, who stepped down after the alleged pro-Russian plot in October to prevent the country from joining Nato, said Moscow "harnessed a lot of destructive material toward Montenegro".
Montenegro is now "in the line" of Moscow's attempts to expand its influence in the war-torn Balkans, and pro-Russian opposition parties are ready to use "bloodshed and a coup" to install a pro-Kremlin government, Mr Djukanovic said while addressing his Socialist Democratic Party youth in the second-largest town of Niksic ahead of local elections.
"A new puppet government would only serve Moscow's interests, which wants to send a message to Europe and Nato that they cannot expand in the Balkans without their (Moscow's) consent," said Mr Djukanovic.
Russian officials have recently named Serbia, Bosnia, Macedonia and Montenegro as Moscow's sphere of interest in the Balkans, saying they should not join Nato.
The former Yugoslav republics were never part of the Soviet bloc and officially all of them want to join the European Union.
Montenegro's prosecutors have accused Russia and its secret service of plotting the election day coup attempt that included alleged plans to kill Mr Djukanovic and take over parliament.
Twenty people, including two Russians, have been accused of taking part.
The Kremlin has repeatedly denied involvement in the plot, but it has openly supported nationalist parties and groups opposed to Montenegro's Nato membership.