KIEV, Ukraine 

Ukrainian Prime Minister Arseniy Yatsenyuk on Saturday urged the U.N. Security Council to convene an emergency meeting after shelling in the southeastern Ukrainian city of Mariupol.

"We are calling on our Western partners and the council's members to immediately gather over the attack in Mariupol," Yatsenyuk said ahead of a meeting attended by top officials of the crisis-hit country.

In remarks to the press, Yatsenyuk accused Russia of trampling on the fundamental values of humanity and international law as well as on the Minsk agreement reached between the Kiev government and pro-Russian separatists in Belarus in September.

He also called for immediate and swift reaction from EU countries after Saturday’s artillery attack, which killed at least 30 people and injured 41 others.

Regional sources said the shelling had hit a multi-story building in Vostochny district, causing several fires in nearby apartments.

Referring to the Russian government, the Ukrainian prime minister said: "The world should do everything to halt this attacker that poses a threat to Ukraine, Europe and the whole world."

In Washington, U.S. Secretary of State John Kerry condemned "in the strongest terms" the "horrific assault by Russia-backed separatists."

"The separatists' new offensive, not just in Mariupol and Debaltseve, but along the cease-fire line, has been aided and abetted by Russia's irresponsible and dangerous decision to resupply them in recent weeks with hundreds of new pieces of advanced weaponry, including rocket systems, heavy artillery, tanks, armored vehicles, in addition to continuing operational command and control," he said.

During a call with Ukrainian President Petro Poroshenko, U.S. Vice President Joe Biden expressed his condolences "for the tragic loss of life in Mariupol," and condemned attacks both in the city and elsewhere as rebels press their advance.

"The Vice President and President Poroshenko expressed grave concern over Russia's blatant disregard for its commitments under the September Minsk agreement and unilateral escalation of the conflict," the White House said in a statement.

- NATO and the EU also condemn the attack

NATO and the European Union also joined in, urging Russia to cease its support of Ukrainian separatists.

NATO chief Jens Stoltenberg in a statement Saturday said he "strongly (urged) Russia to stop its military, political and financial support for the separatists, stop destabilising Ukraine and respect its international commitments."

"Russian troops in eastern Ukraine are supporting these offensive operations with command and control systems, air defense systems with advanced surface-to-air missiles, unmanned aerial systems (drones), advanced multiple rocket launcher systems and electronic warfare systems," Stoltenberg said.

"This further escalation of the open armed conflict has tragic consequences for a population greatly suffering already for far too long," Federica Mogherini, EU's High Representative for Foreign Affairs, said in a statement.

Mogherini said the situation would "inevitably lead to a further grave deterioration of relations between the EU and Russia."

Tensions increased Wednesday when Ukraine's military confirmed it had abandoned Donetsk Airport to pro-Russian separatist militias.

Close to 5,000 people have been killed since April 2014 after pro-Russian rebels seized parts of Luhansk and Donetsk.