KYIV/MARIUPOL: Russia's warplanes bombed Lviv and its missiles struck Kyiv on Saturday, as Moscow followed through on a threat to launch more long-range attacks on Ukrainian cities after its Black Sea Fleet's flagship was sunk.

In besieged Mariupol, scene of the war's heaviest fighting and worst humanitarian catastrophe, Russian troops pressed recent advances, hoping to make up for their failure to capture Kyiv by finally seizing their first big prize of the war.

Moscow said its planes had struck a tank repair factory in the capital, where an explosion was heard and smoke seen in the southeastern Darnytskyi district. Its mayor said rescuers and medics were working there but gave no further details.

Ukraine's military said Russian warplanes that took off from Belarus had also fired missiles at the Lviv region near the Polish border, where four cruise missiles were shot down by Ukrainian air defences.

Across Ukraine to the southeast in Mariupol, journalists in Russian-held parts of the port city reached the Ilyich steel works, which Moscow claimed to have captured on Friday, one of two giant metals plants where defenders have held out in underground tunnels and bunkers.

The factory was reduced to a silent ruin of twisted steel and blasted concrete, with no sign of defenders present. Outside, at least half a dozen civilian bodies were scattered on nearby streets, including a woman in a pink parka and white shoes.

Someone had spraypainted "mined" on a fence by an obliterated filling station forecourt. In a rare sign of life, one red car drove slowly down an otherwise empty street, the word "children" scrawled on a card taped to the windshield.

In Mykolaiv, another a city close to the southern front, Russia said it had struck a military vehicle repair factory.

The bomb and missile attacks followed Russia's announcement on Friday that it would intensify long-range strikes in retaliation for unspecified acts of "sabotage" and "terrorism", hours after it confirmed the sinking of its Black Sea flagship, the Moskva.

Kyiv and Washington say the ship was hit by Ukrainian missiles, a striking display of Ukraine's military success against a far better-armed foe. Moscow says it sank after a fire.

A month and a half into President Vladimir Putin's invasion of Ukraine, Russia is trying to capture territory in the south and east after withdrawing from the north following a massive assault on Kyiv that was repelled at the capital's outskirts.

Russian troops that pulled out of the north left behind towns littered with bodies of civilians, evidence of what U.S. President Joe Biden this week called genocide - an attempt to erase Ukrainian national identity.

Russia denies targeting civilians and says the aim of what it calls its "special military operation" is to disarm its neighbour, defeat nationalists and protect separatists in the southeast.

Ukraine said its troops are still holding out in the ruins of Mariupol, where the defense is concentrated around Azovstal, another huge steel works that has yet to yield.

"The situation in Mariupol is difficult... Fighting is happening right now. The Russian army is constantly calling on additional units to storm the city," defence ministry spokesperson Oleksandr Motuzyanyk told a televised briefing.

"EVACUATE WHILE STILL POSSIBLE"

If Mariupol falls it would be Russia's biggest prize of the war so far. It is the main port of Donbas, a region of two provinces in the south-east which Moscow demands be fully ceded to Russian-backed separatists it has backed since 2014.

Ukraine says it has so far held off Russian advances elsewhere in the Donbas. One person was killed and three wounded in shelling in Luhansk, one of the Donbas provinces, Governor Serhiy Gaidai said in an online post.

A gas pipeline was damaged in the frontline towns of Lysychansk and Severodonetsk, which were without gas and water, Gaidai said in a post on the Telegram messaging app.

"Evacuate, while it is still possible," Gaidai said. Buses were ready for those willing to leave.

Ukraine gained the upper hand in the early phase of a war many Western military experts had predicted it would quickly lose. It has successfully deployed mobile units armed with anti-tank missiles supplied by the West against huge Russian armoured convoys confined to roads by muddy terrain.

But Putin appears determined to capture more Donbas territory to claim victory in a war that has left Russia subject to increasingly punitive Western sanctions and with few allies. All independent media has been shut at home, opposition figures have been jailed or driven abroad and dissent effectively stamped out.

Ukraine's President Volodymyr Zelenskiy said about 2,500 to 3,000 Ukrainian troops have been killed so far, compared to up to 20,000 Russian troops. Moscow has given no updates on its military casualties since March 25, when it said 1,351 had died. Western estimates of Russian losses are many times higher, while there are few independent estimates of Ukraine's losses.

Ukraine says civilian deaths are impossible to count, estimating tens of thousands have been killed in Mariupol alone. Around a quarter of Ukrainians have been driven from their homes, including a tenth of the population that has fled abroad.

"The successes of our military on the battlefield are really significant, historically significant. But they are still not enough to clean our land of the occupiers. We will beat them some more," Zelenskiy said in a late-night video address.

Zelenskiy has appealed to Biden for the United States to designate Russia a state sponsor of terrorism, joining North Korea, Cuba, Iran and Syria, the Washington Post reported. Read full story

A White House spokesperson responded: "We will continue to consider all options to increase the pressure on Putin."