The Ukrainian military said Monday that a group of Russian forces, in the guise of separatist rebels, had crossed into south-east Ukraine with ten tanks and two armored infantry vehicles, aiming to open a new front in the separatist war.

Earlier, a separate military statement said border guards had halted the armored column outside Novoazovsk, Ukraine's most southeasterly point on the Azov Sea, and local residents reached by phone spoke of seeing tanks and other armored vehicles moving near the town.

"This morning there was an attempt by the Russian military in the guise of Donbas fighters to open a new area of military confrontation in the southern Donetsk region," spokesman Andriy Lysenko told journalists.