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.

Donbas is the local name given to Ukraine's industrialised east and the focal point of the pro-Moscow separatist insurgency.

But Foreign Minister Sergei Lavrov dismissed the reports of a Russian incursion, saying: "I haven't heard about it, but