Pro-Russian rebels attack key port; Ukraine says at least 30 dead

A man walks past a burnt-out vehicle after a shelling by pro-Russian rebels of a residential sector in Mariupol, eastern Ukraine, January 24, 2015. REUTERS/Stringer

KIEV (Reuters) - Pro-Russian rebels launched an offensive against the strategic port of Mariupol in eastern Ukraine on Saturday, prompting the European Union's foreign policy chief to warn of a further "grave deterioration" in EU-Russian relations.

Mariupol's city administration said the rebels had killed at least 30 people and injured 83 others by firing rockets from long-range GRAD missile systems.