Ukrainian President Petro Poroshenko condemned Russian “aggression” in a phone call with German Chancellor Angela Merkel and French President Francois Hollande on Monday.

Poroshenko also said shelling by “Russian militants and servicemen” in eastern Ukraine was continuing, despite a ceasefire agreement, the presidency said.

He "also stressed the importance of liberation of all hostages held in the occupied Donbas and in Russia", a statement added.

Ukraine has been wracked by conflict since March 2014 following Russia’s annexation of Crimea after an illegal independence vote.

Fighting between Ukrainian government forces and pro-Russia separatists has seen around 10,000 people killed, according to the UN.