A group of Russian soldiers have crossed the Ukrainian border in armoured vehicles and entered the town of Amvrosiyivka, a Ukrainian military spokesman said.
The report comes amid talks between Russian President Vladimir Putin and Ukraine's Petro Poroshenko aimed at trying to end the five-month conflict between pro-Russian separatists and Ukraine.
Footage of four men, believed to be Russian paratroopers, saying they crossed the Ukrainian border "by accident" was released by the Ukrainian military yesterday.
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The new president of the European Council could be "very important" for David Cameron.