A woman resident passes by a burning house in Mariupol, Ukraine, Saturday, Jan. 24, 2015.
A woman resident passes by a burning house in Mariupol, Ukraine, Saturday, Jan. 24, 2015.

UNITED NATIONS - The U.N.’s political chief urged Russia on Monday to use its influence among separatist rebels in Ukraine to stop hostilities. The appeal comes as the situation has escalated over the past three days, following separate deadly rocket attacks on a bus carrying civilians in Donetsk and shelling in the port city of Mariupol. 

Jeffrey Feltman told an emergency meeting of the U.N. Security Council that more than 5,000 people have been killed since the Ukrainian conflict began early last year. He urged Moscow to press the rebels to adhere to the Minsk agreement, recommit to the September cease-fire and back down from their offensive.

“This will be a critical step in stopping the bloodshed,” he said.

Russia has repeatedly denied Western accusations that it arms, finances and secretly fights alongside the separatists.

Feltman noted that Saturday’s shelling of Mariupol, which killed 30 and wounded more than 100, came from a rebel-held area.

“The OSCE [Organization for Security and Cooperation in Europe] Special Monitoring mission reported, based on crater analysis, that the rockets originated from territory controlled by the so-called 'Donetsk People’s Republic,'” he said.

He said that city lies outside the immediate conflict zone and the conclusion could be drawn that the perpetrators of the attack knowingly targeted civilians - which is an international crime.

U.S. Ambassador Samantha Power reiterated Washington’s outrage at Moscow’s hand in the conflict, saying Russia is trying “to play the international community for the fool” by blaming the surge in violence on the Ukrainian government.

“This offensive is made in Moscow," she said. "It is waged by Russian-trained and Russian-funded separatists who use Russian missiles and Russian tanks, who are backed up by Russian troops and whose operations receive direct Russian assistance.”

Russian envoy Vitaly Churkin said Moscow is “seriously concerned” by the escalation. He said his government has consistently urged the parties toward direct talks and he accused Washington of “egging on the Ukrainian hawks,” pushing them toward a military solution of the conflict.