Pro-Russian separatists had warned they would seize businesses in areas they control unless the Ukrainian government ends a rail blockade that has halted coal shipments from rebel territory.

United Nations officials say 1 million children urgently need humanitarian aid in eastern Ukraine, and the number has nearly doubled in a year.

A fresh contingent of Canadian troops has arrived in eastern Europe to take part in NATO exercises meant to reassure jittery allies and the deployment follows a spike in violence between Ukrainian forces and Russian-backed separatists.