Ukrainian officials say the strategically important coastal city of Mariupol has come under rocket fire, and one says 10 people were killed.

Mariupol lies on the Azov Sea and is the major city between mainland Russia and the Russia-annexed Crimean Peninsula. Heavy fighting in the region in the autumn raised fears that Russian-backed separatist forces would try to establish a land link between Russia and Crimea. Rebel forces have positions around 10 kilometers (six miles) from Mariupol's eastern outskirts.

The press center for the anti-rebel operation said Grad missiles struck the eastern area on Saturday morning, destroying residential buildings.

Regional police official Vyacheslav Abroskin said on Facebook that 10 people were killed.