'Powerful bombs' rock Ukraine's besieged Mariupol amid new rescue bid

Two "super powerful bombs" rocked Mariupol on Tuesday as Ukrainian authorities made a fresh attempt at rescuing civilians from the besieged port city which has suffered relentless shelling since Russia's invasion began almost a month ago. 

More than 200,000 people are trapped in the strategic city described by those who managed to escape as a "freezing hellscape riddled with dead bodies and destroyed buildings", Human Rights Watch said, quoting figures provided by a local official.

"We know that there will not be enough space for everyone" on Tuesday, but "we will try to carry out the evacuation until we have gotten all the inhabitants of Mariupol out," vowed Deputy Prime Minister Iryna Vereshchuk in a video address.

Two "super powerful bombs" slammed into the city even as rescue efforts were ongoing, said Mariupol local authorities, without giving an immediate toll.

"It is clear that the occupiers are not interested in the city of Mariupol, they want to raze it to the ground, to reduce it to ashes," the authorities said.

Ukrainian leader Volodymyr Zelensky turned to Pope Francis for help, urging the pontiff to mediate in the conflict and to help end "human suffering".

Earlier, Zelensky said all issues would be on the table if Russia's Vladimir Putin agreed to direct talks to end the war, including the contested eastern regions Donbas and the annexed Crimea peninsula.

But he warned his country would be "destroyed" before it surrenders.

The Kremlin in return said it would like to see negotiations with Kyiv to be "more active and substantial".

Since Russia launched its invasion on February 24, at least 117 children have been killed in the war, Ukraine's federal prosecutor said. 

Some 548 schools have been damaged, including 72 completely destroyed.

Russia has pushed on with its assaults, in the face of unprecedented Western sanctions that has led international companies to pull out of the country and left its key banks shut out of the SWIFT messaging system. 

But both Western and Ukrainian experts believe the war was not going the way the Kremlin had planned.