"Over the last day, we have lost seven Ukrainian soldiers, and another 24 were injured as a result of military clashes," he said.

The fighting in eastern Ukraine has worsened significantly in recent weeks, with militants launching attacks to gain control of Donetsk airport and advance into other areas all along the front line.

On Saturday the Ukrainian held city of Mariupol was hit by a deadly rocket attack that killed around 30 civilians and wounded more than 100. The OSCE has reported that the rockets were fired from two areas to the north-east and east of the city that are controlled by the militants.