The territory controlled by the self-proclaimed Donetsk and Luhansk People's Republics in southeast Ukraine has contracted by three quarters, Ukraine's National Security and Defense Council (NSDC) says.

"During the time of the anti-terrorist operation the territory occupied by terrorists has contracted by three quarters which means that one quarter is still controlled by terrorists," spokesman for the NSDC information and analysis center Andriy Lysenko said at a Sunday briefing in Kyiv.

He said that the active phase of the operation is now under way and "we have enough arms and ammunition to win."