Ukrainian President Petro Poroshenko says the armed conflict in Donbas has been escalating, and there is no progress in freeing the captives.

"President Poroshenko stated the escalation of the conflict and the absence of real progress in the fulfillment of the Minsk agreements, particularly the liberation of hostages," the Ukrainian presidential press service said in a report on its English-language webpage following Poroshenko's telephone conversation with Finnish President Sauli Niinisto.

The parties agreed on the importance of considering the extension of the EU's sanctions against Russia.

Poroshenko also insisted on observing the fundamental principles of the Helsinki Final Act of 1975, particularly in the run-up to the 40th anniversary of its conclusion and the holding of an OSCE Parliamentary Assembly jubilee session in Finland.

Talking about Crimea's "illegal annexation" by Russia and its aggression in Donbas, Poroshenko described this as "brutal violations of these fundamental principles, particularly territorial integrity and sovereignty of an independent state," the report says.