Russian forces have cut off the last routes for evacuating citizens from the eastern Ukrainian city of Sievierodonetsk, a Ukrainian official says, as the Kremlin pushes for victory in the Donbas region.

The last bridge to the city was destroyed, trapping any remaining civilians and making it impossible to deliver humanitarian supplies, said regional governor Sergei Gaidai, adding that 70 per cent of the city was under Russian control.

Ukraine has issued increasingly urgent calls for more Western heavy weapons to help defend Sievierodonetsk, which Kyiv says could hold the key to the battle for the eastern Donbas region and the course of the war, now in its fourth month.

Late on Monday, President Volodymyr Zelenskiy said the battle for the eastern Donbas would go down as one of the most brutal in European history. The region, comprising the provinces of Luhansk and Donetsk, is claimed by Russian separatists.

“For us, the price of this battle is very high. It is just scary,” he said on Monday.

“We draw the attention of our partners daily to the fact that only a sufficient number of modern artillery for Ukraine will ensure our advantage.”

Russia’s main goal is to protect Donetsk and Luhansk, Kremlin spokesperson Dmitry Peskov said after the leader of one of the separatist regions asked for additional forces from Moscow.

Ukraine needed 1000 howitzers, 500 tanks and 1000 drones among other heavy weapons, presidential adviser Mykhailo Podolyak said.

Moscow issued the latest of several recent reports saying it had destroyed US and European arms and equipment.

Russia’s 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.

Ukraine’s interior ministry said on Telegram that Udachne had been hit by a Russian strike overnight Sunday into Monday, without mentioning whether weapons had been targeted.

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

The European Commission would recommend granting Ukraine official status as an EU candidate country, Politico reported late on Monday, citing several unnamed officials.

Commission President Ursula von der Leyen said on Saturday the EU executive’s opinion on Ukraine’s request to join would be ready by the end of this week.

Russia’s RIA news agency quoted a pro-Moscow separatist spokesperson Eduard Basurin as saying Ukrainian troops were blockaded in Sievierodonetsk and should surrender or die.

The situation risked becoming like Mariupol, “with a large pocket of Ukrainian defenders cut off from the rest of the Ukrainian troops”, according to Damien Magrou, spokesperson for the International Legion for the Defence of Ukraine that has had forces in Sievierodonetsk.

During the fall of Mariupol last month, hundreds of civilians and badly wounded Ukrainian soldiers were trapped for weeks in the Azovstal steelworks.

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 that has killed thousands of civilians and raised fears of wider conflict in Europe.

More than five million people have fled and the world has been hit by a food and energy crisis, dividing Western nations over how to handle it.

After failing to take the capital Kyiv following the February 24 invasion, Moscow focused on expanding control in the Donbas, where pro-Russian separatists have held territory since 2014. Russia has also tried to capture more of Ukraine’s Black Sea coast.

“The entire front is being subjected to constant shelling,” Donetsk regional governor Pavlo Kyrylenko told Ukrainian TV on Monday evening.

The towns of Maryinka, Krasnohorivka, Vuhledar were hit in the coal-producing belt and Avdiivka, home to a big coking plant, he said.