Ukraine accuses Russia of 'undisguised aggression' as rebels advance

Ukrainian President Petro Poroshenko holds a news conference at the European Council headquarters during an EU summit in Brussels August 30, 2014. REUTERS/Laurent Dubrule

KIEV/MOSCOW (Reuters) - Ukrainian President Petro Poroshenko accused Russia on Monday of "direct and undisguised aggression" which he said had radically changed the battlefield balance as Kiev's forces suffered a further reverse in their war with pro-Moscow separatists.

In the latest in a string of setbacks in the past week, Ukraine's military said it had pulled back from defending a vital airport in the east of the country, near the city of Luhansk, where troops had been battling a Russian tank battalion.