French President Francois Hollande held talks with his Ukrainian counterpart Petro Poroshenko and European Council chief Donald Tusk on Sunday to express his "very strong concern" over the surge in violence in eastern Ukraine, the presidency said.

It added that Hollande was also due to speak with Russian President Vladimir Putin and German Chancellor Angela Merkel on Monday to discuss the escalation of fighting, after heavy rocket fire killed 30 civilians in the strategic port of Mariupol on Saturday.