Ukrainian President Petro Poroshenko has extended a truce with pro-Russian rebels by another 72 hours, according to reports from the Ukrainska Pravda news site.
The decision was reached following urgent consultation between Mr Poroshenko and his defence officials following his arrival in Kiev from an EU summit in Brussels at which he signed an historic trade and political association pact with the EU.
The UN has reported that an estimated 110,000 people have fled to Russia from Ukraine while more than 54,000 have been displaced inside the conflict-torn country.
"Since the start of 2014, 110,000 Ukrainians have arrived in Russia," said Melissa Fleming, spokeswoman for the UN's refugee agency.
She said that most were thought to be from the east of the country.
"Within Ukraine itself, 16,400 people have fled their homes in the east in the past week alone, taking the total number of internally-displaced to 54,400," Ms Fleming added.
Meanwhile, French President Francois Hollande and German Chancellor Angela Merkel will talk with Russia's Vladimir Putin and Ukraine's Petro Poroshenko over the phone on Sunday to assess the situation in Ukraine, Mr Hollande said.
Referring to EU demands that Ukrainian rebels agree to ceasefire verification arrangements, to free hostages and launch serious talks on implementing Mr Poroshenko's peace plan, Mr Hollande told reporters: "If there is no progress on these three points,the Council (of EU member states) ... would take more measures."
Mr Putin has called for a long-term ceasefire in Ukraine to allow talks between representatives of Kiev and eastern regions, where rebels are waging an armed insurgency.
Mr Putin also said during a diplomatic ceremony in the Kremlin that violence has forced tens of thousands of Ukrainians to seek refuge, including in Russia.
Ukraine's Poroshenko signs EU accord
Earlier, Ukrainian President Poroshenko said the signing of an association accord with the EU marked a "historic day" that offered his ex-Soviet country a fresh start after years of political instability.
The accord, which has been at the heart of the country's political crisis, was signed at a ceremony in Brussels this morning.
It will seal closer political and economic ties between Ukraine and the European Union.
Mr Poroshenko said the pact offered "an absolutely new perspective for my country ... it is a historic day, the most important day since independence".
Russia immediately said "grave consequences" would follow.
Ukraine's former pro-Moscow president Viktor Yanukovych turned his back on signing the EU agreement last November in favour of closer ties with Moscow.
That move prompted months of street protests, which eventually led to his fleeing the country.
Soon afterwards, Russia annexed Ukraine's Crimea region, drawing outrage and sanctions from the United States and EU.
Georgia and Moldova signed similar deals, holding out the prospect of deep economic integration and unfettered access to the EU's 500 million citizens.
President Putin today said that Ukrainian society is split after being forced to choose between Europe and Russia.
"The anti-constitutional coup in Kiev, the attempts to impose an artificial choice between Europe and Russia have pushed society to a split, to a painful internal confrontation," Mr Putin said.