Russia said on Thursday that a fragile peace deal for eastern Ukraine faced a "constant threat" of breaking down because of Kiev's actions, as fighting surged in the ex-Soviet state.

"The February 12 Minsk agreements are under constant threat of breaking down because of the actions of the Kiev authorities who are trying to avoid fulfilling their obligations to establish direct dialogue with the Donbass," Foreign Minister Sergei Lavrov said, referring to pro-Moscow rebel-controlled territory.