A Ukrainian servicewoman walks at a position, as Russia's attack on Ukraine continues, in Luhansk Region, Ukraine April 26, 2022.
A Ukrainian servicewoman walks at a position, as Russia's attack on Ukraine continues, in Luhansk Region, Ukraine April 26, 2022. Reuters / SERHII NUZHNENKO

Russian forces swarmed into the eastern Ukrainian city of Sievierodonetsk and pounded a zone where hundreds of civilians were sheltering, a Ukrainian official said on Monday - a scene that mirrored Moscow's assault on Mariupol last month.

Pro-Moscow separatists claimed the last bridge out of Sievierodonetsk had been destroyed and Ukrainian defenders there must now surrender or die. Ukraine said there was still another way out, although that route was severely damaged.

Ukraine has issued increasingly urgent calls for more Western weapons to help defend Sievierodonetsk, which Kyiv says could hold the key to the outcome of the battle for control of the eastern Donbas region and the future course of the war.

"The battles are so fierce that fighting for not just a street but for a single high-rise building can last for days," regional governor Sergei Gadai said on social media.

Russian forces now controlled about 70% of Sievierodonetsk, he said, and were destroying it "quarter by quarter" in one of the bloodiest assaults since they launched their invasion on Feb. 24.

"Russians continue to storm the city, having a significant advantage in artillery they have somewhat pushed back the Ukrainian soldiers," said Gaidai, who is governor of the Luhansk region that includes Sievierodonetsk.

Russian artillery fire pummelled the Azot chemical plant, where hundred of civilians were sheltering, he said.

"About 500 civilians remain on the grounds of the Azot plant in Sievierodonetsk, 40 of them are children. Sometimes the military manages to evacuate someone," he said, noting the lack of a cease-fire agreement or agreement on evacuation corridors.

Russia's RIA news agency quoted a pro-Moscow separatist spokesperson, Eduard Basurin, as saying the last bridge over the Siverskyi Donets river linking Sievierodonetsk and its Ukrainian-held twin city Lysychansk had been destroyed on Sunday. Ukrainian troops were effectively blockaded in Sievierodonetsk and should surrender or die, he said.

Gaidai also said one crossing was destroyed on Sunday, but there was still another "half destroyed" bridge remaining, though it could not be used for heavy vehicles.

IMAGE OF RUSSIA

Ukraine's account of civilians trapped in an industrial plant echoed the fall of Mariupol last month, where hundreds of civilians and badly wounded Ukrainian soldiers were evacuated after being trapped for weeks in the Azovstal steelworks.

Ukrainian officials have expressed concern about the fate of troops who surrendered after many were taken to Russia, and say cholera is spreading among remaining residents due to bodies left buried in rubble from destroyed residential buildings.

Ukrainian President Volodymyr Zelenskiy said severe fighting was ongoing in the Donbas, "literally for every metre" and that child casualties of attacks had created a lasting image of Russia for the rest of the world.

"Not Peter the Great, not Lev Tolstoy, but children injured and killed in Russian attacks," he said on Sunday in his nightly video address, apparently referring to President Vladimir Putin's comparison of Moscow's military campaign to Russian emperor Peter the Great's 18th century conquest of lands held by Sweden.

Russia has denied targeting civilians in what it calls a "special operation" to restore Russian security and "denazify" its neighbour. Ukraine and its Western allies call this a baseless pretext for an invasion which has killed thousands of civilians and raised fears of wider conflict in Europe.

More than five million people have fled the assault and millions more are threatened by a global energy and food crisis due to disrupted gas, oil and grain supplies from Russia and Ukraine. Western nations are divided over how best to end it.

Gaidai said a six-year-old child was among those killed in the latest shelling of Lysychansk. The news agency of the Russian-backed separatist-controlled Donetsk region said at least three people, including a child, were killed by Ukrainian shelling that hit a market in Donetsk city. Reuters could not verify either report.

BURNING CROPS

After failing to take the capital Kyiv, Moscow focused on expanding control in the Donbas, where pro-Russian separatists have held territory since 2014, while also trying to capture more of Ukraine's southern Black Sea coast.

Along the front line in the Donbas, the fighting poses a new threat as the weather warms, with shelling and rocket fire setting fields on fire and destroying ripening crops.

Lyuba, a resident in the Ukrainian-held pocket of the Donbas near the front, watched a fire blazing along the fields but said she was not planning to leave. "Where can I go? Who is waiting for me there?" she said. "It's scary. But it is what it is."

In Sievierodonetsk, Ukrainian and Russian forces were both suffering heavy losses, Roman Vlasenko, head of Sievierodonetsk district administration, told local TV.

"Our boys are holding on but the conditions are tough," he said. Vlasenko said the city had been without communications and normal services for a month and Russia was throwing in reinforcements.

The battle was preventing Russian forces making headway in the south, Ukrainian Interior Ministry adviser Vadym Denysenko said.

Ukrainian Presidential Adviser Mykhailo Podolyak listed equipment he said was needed for heavy weapons parity, including 1,000 howitzers, 500 tanks and 1,000 drones.

"We are waiting for a decision," he said, adding that Western defence ministers would meet on Wednesday in Brussels.

Russia issued the latest of several recent reports saying it had destroyed U.S. and European arms and equipment, hoping to send the message that delivering more would be futile.

The defence ministry said high-precision air-based missiles had struck near the railway station in Udachne northwest of Donetsk, hitting equipment that had been delivered to Ukrainian forces. There was no immediate word from the Ukrainian side.

Moscow has criticised the United States and other nations for sending Ukraine weapons, threatening to strike new targets if the West supplied long-range missiles.