ZAPORIZHZHIA, UKRAINE (REUTERS) - Russia unleashed rockets on Tuesday (May 3) on an encircled steel works in Mariupol, Ukraine’s last redoubt in the port city, after a ceasefire broke down with some civilians still trapped beneath the sprawling site despite a UN-brokered evacuation.

Scores of evacuees who did manage to leave under United Nations and Red Cross auspices over the weekend after cowering for weeks under the Azovstal plant reached the relative safety of Ukraine-controlled Zaporizhzhia.

More than 200 civilians remain in the plant, according to Mariupol Mayor Vadym Boichenko, with 100,000 civilians still in the city that has been devastated by weeks of Russian siege and shelling.

Weary-looking people, including children and the elderly, clambered off buses after escaping the ruins of their home town in south-east Ukraine where Russia now claims control.

“We had said goodbye to life. We didn’t think anyone knew we were there,” said Valentina Sytnykova, 70, who said she sheltered in the plant for two months with her son and 10-year-old granddaughter.

Fresh Russian attacks in Ukraine’s eastern Donetsk region killed 21 civilians and injured 27 on Tuesday, regional governor Pavlo Kyrylenko said.

He said the figure, which included 10 dead at a coking plant in the town of Avdiivka reported earlier, was the highest daily death toll in the region since an attack on a railway station in Kramatorsk last month that killed more than 50 people.

Russia has turned its heaviest firepower on Ukraine’s east and south after failing to take Kyiv, the capital, in a drive to limit Ukraine’s access to the Black Sea, vital for its grain and metal exports.

Ukrainian President Volodymyr Zelensky accused Russia of breaching agreements to pause fighting long enough to allow vulnerable civilians to be moved to safety, even the UN-coordinated operation at the steel works in Mariupol.

“They’re still fighting. They’re still bombarding and shooting. So we need some ceasefire. We need a breather,” Zelensky said via video link at a Wall Street Journal event..

Moscow has also struck targets much farther west to disrupt supplies of Western military aid to Zelensky’s forces.

On Tuesday Russia’s defence ministry said its forces had struck a military airfield near the port of Odesa with missiles destroying drones, missiles and ammunition supplied to Ukraine by the United States and its European allies. Ukraine said three missiles targeted the Odesa region and all were intercepted.

Andriy Sadoviy, the mayor of Lviv, a western city near the Polish border, said late on Tuesday that air strikes had damaged power stations, cutting off electricity in some districts.

Olesksandr Kamyshin, head of Ukrainian railways, said Russian forces struck six stations in the center and west of the country. There were no injuries among rail workers or passengers, he said on Twitter.

Two Russian missile strikes in central Kirovohrad resulted in an unspecified number deaths and injuries, the Ukrainian armed forces southern district said.

‘Ukraine's finest hour’

Nearly 10 weeks into a war that has killed thousands, destroyed cities and driven five million Ukrainians to flee abroad, Russian President Vladimir Putin raised the economic stakes for Kyiv’s Western backers on Tuesday by announcing plans to block the export of vital Russian raw materials.

“If you don’t stand up to dictators, history has shown us, they keep coming, they keep coming,” US President Joe Biden told assembly line workers at a Lockheed Martin plant in Alabama that produces the Javelin anti-tank missile, a weapon that has helped Ukraine fight Russia’s invasion.

Biden used the visit to press the US Congress to approve his proposed US$33 billion (S$46 billion) assistance package for Ukraine, including more than US$20 billion in military aid.

The European Union said new sanctions on Russia would target its oil industry and banks, and that it also planned to replace two-thirds of its Russian gas use by the end of 2022, part of efforts to deplete Moscow’s war chest.

British Prime Minister Boris Johnson announced an additional 300 million pounds (S$500 million) in aid, and told Ukrainian lawmakers by video link it was “ Ukraine’s finest hour,” echoing wartime leader Winston’s Churchill’s famous words to Britons.

French President Emmanuel Macron urged Putin in a phone call on Tuesday to order an immediate ceasefire in Ukraine and to lift Russia’s embargo on Ukrainian exports via the Black Sea.

Putin said Russia remained open to dialogue, the Kremlin said.

Zelensky put the preliminary cost of war damage in Ukraine so far at around US$600 billion. He urged foreign companies to pull out of the Russian market because not doing so “means you are directly supporting that war machine.”

Pummelled by Western sanctions, Russia’s own US$1.8 trillion economy is heading for its biggest contraction since the years following the 1991 break-up of the Soviet Union.

Under the decree signed by Putin on Tuesday, Russia’s government has 10 days to draw up a sanctions list targeting specific people and entities in “unfriendly” states.

‘Powerful assault’

Mariupol, a city of 400,000 before Russia launched its invasion on Feb 24, has seen the bloodiest fighting of the war, enduring weeks of siege and shelling.

In a Telegram video from the steel plant, Captain Sviatoslav Palamar of Ukraine’s Azov Regiment said Russia had pounded Azovstal with naval and barrel artillery through the night and dropped heavy bombs from planes.

“As of this moment, a powerful assault on the territory of the Azovstal plant is under way with the support of armoured vehicles, tanks, attempts to land on boats and a large number of infantry,” Palamar said.

Reuters could not independently verify his account. However, Reuters images on Monday showed volleys of rockets fired from a Russian truck-mounted launcher towards Azovstal.