By Louis Charbonneau and Michelle Nichols
UNITED NATIONS (Reuters) - The deadly rocket attacks on the government-held port city of Mariupol in eastern Ukraine last weekend were a war crime because they intentionally targeted civilians, a senior U.N. official said on Monday.
U.N. political affairs chief Jeffrey Feltman told an emergency meeting of the 15-nation Security Council on Ukraine that crater analysis by the Organization for Security and Cooperation in Europe indicated the shelling came from rebel-controlled territory.
"The entity which fired these rockets knowingly targeted a civilian population," he said. "This would constitute a violation of international humanitarian law."
Some 30 civilians were killed in the Mariupol attack, according to the Kiev government, which blames rebels for the assault. Moscow maintains Kiev is to blame for the latest fighting for refusing to pull its heavy weapons from the front and negotiate with the rebels.
"We also urge the leadership of the Russian Federation to use their influence to call on the rebels to cease hostilities immediately," Feltman said. "This will be a critical step in stopping the bloodshed."
In his speech, Russia's U.N. Ambassador Vitaly Churkin repeated Moscow's position that Kiev caused the renewed fighting.
"Stop egging on the Ukrainian hawks," Churkin appealed to Western governments. "The only thing that will lead to is an even greater catastrophe."
U.S. Ambassador Samantha Power accused Moscow of plotting to grab more of neighboring Ukraine.
"Russia's end goal remains ... to seize more territory and move the line of Russian-controlled territory deeper and deeper into Ukraine," she said.
"This offensive is made in Moscow," Power added. "It is waged by Russian-trained and Russian-funded separatists, who use Russian missiles and Russian tanks, who are backed up by Russian troops."
Over the weekend Russia blocked a proposed council statement that would have condemned the Mariupol attack as well as statements by a separatist leader who announced the offensive against Mariupol and repudiated the Minsk peace agreement from September.
Lithuanian Ambassador Raimonda Murmokaite dismissed Russia's denials of aiding the rebels.
"How can they afford modern tanks, each of which costs at least $4 million," she said. "How can hundreds of Russian soldiers be dying on Ukraine's soil if they are not even there?"
The council has been deadlocked on Ukraine since the start of the conflict a year ago. Russia, which Western council members accuse of sending troops and weapons to bolster the separatists in Ukraine, has veto powers and can block all council action.
(Reporting by Louis Charbonneau and Michelle Nichols; Editing by Cynthia Osterman)