The Foreign Ministry is also calling on Russia to halt aid to the rebels. "We are appealing to the Russian Federation once more to use its influence on the separatist leaders in east Ukraine and to halt military, political and financial aid to the separatists," the ministry said.

Intentional infliction of suffering on civilians, among them children and the elderly, is completely unacceptable and a violation of international law, the press release also said.

The ministry reiterated Slovenia's position that the conflict in Ukraine can be resolved peacefully, calling on the sides to implement the obligations laid down in Minsk treaties.

At least 30 people were killed and some 100 injured in a series of attacks on a residential area in Mariupol.