Zelenskyy calls for Israel's Iron Dome missile defence system, as Russians bomb Mariupol art school sheltering 400 residents

Russian forces are being accused of bombing an art school sheltering 400 residents in the besieged Ukrainian port city of Mariupol, while President Volodymyr Zelenskyy is appealing to Israel for help pushing back the Russia's assault on his country.

Key points: Volodymyr Zelenskyy said Russia has not collected the bodies of its dead in some places

Volodymyr Zelenskyy said Russia has not collected the bodies of its dead in some places A Mariupol police officer said the city has been "wiped off the face of the Earth"

A Mariupol police officer said the city has been "wiped off the face of the Earth" A marine barracks was destroyed in the city of Mykolaiv, killing 40, a Ukrainian military official said

During a video link address to the Israeli parliament, Mr Zelenskyy questioned Israel's reluctance to sell its Iron Dome missile defence system to Ukraine.

It was the latest in a series of appeals he has made for help from abroad.

"Everybody knows that your missile defence systems are the best … and that you can definitely help our people, save the lives of Ukrainians, of Ukrainian Jews," Mr Zelenskyy, who is of Jewish heritage, said.

Israeli Prime Minister Naftali Bennett has held numerous calls with both Mr Zelenskyy and Russian President Vladimir Putin in recent weeks to try to end the conflict.

The UN human rights office said at least 902 civilians had been killed in the war as of midnight Saturday, though it says the real toll is probably much higher.

Ukrainian prosecutors say 112 children have been killed.

Earlier on Sunday, Mr Zelenskyy said Russian soldiers were being sent "to the slaughter" as fierce fighting raged in parts of the country.

He accused the Russian military of not recovering the bodies of its fallen troops.

"In places where there were especially fierce battles, the bodies of Russian soldiers simply pile up along our line of defence. And no one is collecting these bodies," he said in a video address to the nation.

He described a battle near Chornobayivka in the south, where Ukrainian forces held their positions and six times beat back the Russians, who kept "sending their people to slaughter".

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 38 seconds 38 s Volodymyr Zelenskyy says the Russian leadership keeps "sending their people to slaughter".

The night-time address came as fighting continued in Mariupol and a marine barracks was destroyed in Mykolaiv.

He also said the siege of Mariupol would go down in history for what he said were war crimes committed by Russia's military.

"To do this to a peaceful city, what the occupiers did, is a terror that will be remembered for centuries to come," he said.

Mr Zelenskyy told Ukrainians the ongoing negotiations with Russia were "not simple or pleasant, but they are necessary".

"Ukraine has always sought a peaceful solution. Moreover, we are interested in peace now," he said.

Russia is not collecting the dead bodies of its soldiers, Volodymyr Zelenskyy says. ( Reuters )

Estimates of Russian deaths in Ukraine vary widely, yet even conservative figures are in the low thousands.

That's a much faster pace than in previous Russian offensives, threatening support for the war among ordinary Russians.

Dmitry Gorenburg, a researcher on Russia's security at the US-based CNA think tank, said Russia's number of dead and wounded in Ukraine was nearing the 10 per cent benchmark of diminished combat effectiveness.

The reported battlefield deaths of four Russian generals — out of an estimated 20 in the fight — signalled impaired command, he said.

What else is happening in Mariupol?

In Mariupol, which has suffered some of the heaviest bombardment since Russia launched its invasion on February 24, many of its 400,000 residents remain trapped in the city with little, if any, food, water and power.

Fighting continued inside the city on Sunday, regional governor Pavlo Kyrylenko said, without elaborating.

Intense street fighting continues in Mariupol, weeks into a devastating Russian siege. ( AP: Planet Labs PBC )

Capturing Mariupol would help Russian forces secure a land corridor to the Crimean peninsula that Moscow annexed from Ukraine in 2014.

The city council said on its Telegram channel late on Saturday that several thousand residents had been "deported" to Russia over the past week.

Russian news agencies said buses had carried hundreds of people Moscow calls refugees from Mariupol to Russia in recent days.

Russian forces bombed an art school on Saturday in which 400 residents were sheltering, but the number of casualties was not yet known, Mariupol's council said.

Reuters could not independently verify the claim.

A day after Russian forces cut off Mariupol's access to the Sea of Azov, Ukraine's interior minister said intense fighting in the city continued, and the key Azovstal steel plant had been damaged.

An adviser to Mr Zelenskyy said there was no immediate military help available for Mariupol, as the nearest forces able to assist were already struggling against Russian forces at least 100 kilometres away.

In a video post from a rubble-strewn street, Mariupol police officer Michail Vershnin pleaded to Western leaders for help.

"Children, elderly people are dying," he said.

"The city is destroyed and it has been wiped off the face of the earth."

In Mykolaiv, rescuers on Saturday searched the rubble of a marine barracks that was destroyed in an apparent missile attack a day earlier.

It is not clear how many marines were inside at the time, but a senior Ukrainian military official, who spoke to The New York Times on condition of anonymity to reveal sensitive information, estimated that as many as 40 marines were killed.

Around Kyiv, the capital's north-western suburbs of Bucha, Hostomel, Irpin and Moshchun were under fire Saturday, according to the Kyiv regional administration. It said Slavutich, 165 kilometres north of the capital, was "completely isolated."

More than 6,000 people were able to evacuate along eight of 10 humanitarian corridors Saturday, according to Deputy Prime Minister Iryna Vereshchuk. That figure included 4,128 people from Mariupol, who were taken to the south-eastern city of Zaporizhzhia.

In Zaporizhzhia, a 38-hour curfew was in effect until 6am Monday after two missile strikes on the city's suburbs killed nine people. Local authorities said they continue to evacuate people from areas occupied by Russian troops.

Thousands of refugees are fleeing Ukraine for neighbouring countries. ( AP: Sergei Grits )

The Russian military said on Sunday that it carried out a new series of strikes on Ukrainian military facilities with long-range hypersonic and cruise missiles.

Russian Defence Ministry spokesman Major General Igor Konashenkov said a Kinzhal hypersonic missile hit a Ukrainian fuel depot in Kostiantynivka near the Black Sea port of Mykolaiv.

The strike marked the second day in a row that Russia used the Kinzhal, a weapon capable of striking targets 2,000 kilometres away at a speed 10 times the speed of sound.

The previous day, the Russian military said the Kinzhal was used for the first time in combat to destroy an ammunition depot in Diliatyn in the Carpathian Mountains in western Ukraine.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 5 minutes 15 seconds 5 m Ukraine's unlikely hero: Volodymyr Zelenskyy