Ukrainian Prime Minister Arseniy Yatsenyuk on Saturday called for an urgent meeting of the United Nations Security Council over the shelling of the city of Mariupol that claimed the lives of at least 21 people.

"Today I held a meeting with the ambassadors of Big Seven and ambassadors of countries-members of the UN Security Council,”  Yatsenyuk said during a session of the emergency response centre as quoted by kyivpost.com.

"We call on our Western partners and the UN Security Council to immediately convene a UN Security Council meeting."

Ukrainian government officials accused pro-Russian rebels in eastern Ukraine of launching the deadly shelling earlier on Saturday.

Representative of the self-proclaimed Donetsk People's Republic, however, rejected the accusations, telling RIA Novosti the rebels had no artillery systems near Mariupol that could allow shelling of the affected area.

The shelling, in which Grad multiple rocket launchers were reportedly used, came just a day after rebel leaders said they were pulling out of peace talks and vowed to push their offensive all the way to the borders of Donetsk region.

While initial reports said 15 people had lost their lives in the shelling, the prosecutor's office of the Donetsk region said in a mid-afternoon statement that 21 people had been killed.