Ukrainian President Petro Poroshenko accused Russia on Monday, Sept 1, of launching "direct and open aggression" which he said had radically changed the balance on the battlefield against Kiev in its fight against pro-Russian armed groups, Reuters reported.

"Direct and open aggression has been launched against Ukraine from a neighboring state. This has changed the situation in the zone of conflict in a radical way," he said in a speech at a military academy in Kiev.

Following events last week in Ukraine, when government forces suffered major reverses against the rebels, there would be high-level personnel changes in the Ukrainian armed forces, he said.