Heavy rockets that killed at least 30 people on Saturday in Ukraine's government-held port of Mariupol were fired from territory controlled by pro-Russian rebels, international monitors said.
The Organization for Security and Co-operation in Europe (OSCE) said its inspection team concluded that "the Grad rockets originated from a northeasterly direction... and the Uragan rockets from an easterly direction, both controlled by the 'Donetsk People's Republic'."
The self-proclaimed separatist region's leader had earlier announced the launch of a major new offensive against Mariupol but did not acknowledge direct responsiblity for the rocket attacks.