Ukraine has said Russian soldiers captured after crossing the border were on a "special mission," contradicting a Russian defence ministry source's claim that it was accidental, Reuters reported.
"This wasn't a mistake, but a special mission they were carrying out," Ukrainian military spokesman Andriy Lysenko said.
Lysenko also claimed that pro-Russian separatists were attacking the southeastern border town of Novoazovsk "at this very minute."
He added that 12 Ukrainian service members had been killed during fighting in the past 24 hours.
Were the Russians -as Barack Obama claims - weighed down by sanctions, or where the Ukrainians looking to cut their losses?
The new president of the European Council could be "very important" for David Cameron.