U.S. Vice President Joe Biden in phone conversation with Ukrainian President Petro Poroshenko strongly criticized statements by militants' leaders, who control a part of Donetsk and Luhansk regions, indicating their intention to take additional territory.

"The Vice President also strongly criticized statements by separatist leaders indicating their intention to take additional territory and hold local elections outside of the Ukrainian legal framework in direct contravention of the Minsk agreements of September 2014 and February 2015," reads a statement published by White House.

The two leaders discussed the situation in the eastern part of the country and condemned the escalation of attacks by combined Russian-separatist forces, to include attacks on OSCE monitors.