Russian troops storm Sievierodonetsk as Donbas suffers heavy bombardment

Russian and Ukrainian troops engaged in close-quarter combat in an eastern Ukraine city on Sunday as Moscow's soldiers, supported by intense shelling, attempted to gain a strategic foothold in the region while facing fierce Ukrainian resistance.

Ukrainian regional officials reported that Russian forces were "storming" the eastern city of Sievierodonetsk, where the fighting has knocked out power and cellphone services and terrorized civilians who haven't fled.

Sievierodonetsk, a manufacturing centre, has emerged as the focal point of Russia's quest to conquer Ukraine's industrial Donbas region. Russia also stepped up its efforts to take nearby Lysychansk, where Ukrainian officials reported constant shelling.

The two cities, with a combined prewar population of around 200,000, are the last major areas under Ukrainian control in Luhansk province, which makes up the Donbas together with neighbouring Donetsk. Russia is focused on capturing parts of both not already controlled by pro-Moscow separatists.

Russian forces made small advances in recent days as bombardments chewed away at Ukrainian positions and kept civilians trapped in basements or desperately trying to get out safely. Attacks to destroy military targets throughout the country also caused casualties in civilian areas.

In his Saturday night video address, Ukrainian President Volodymyr Zelenskyy described the situation in the east as "very complicated'' and "indescribably difficult." The "Russian army is trying to squeeze at least some result'' by concentrating its attacks there, he said.

Sievierodonetsk Mayor Oleksandr Striuk said there was fighting at the city's bus station on Saturday. A humanitarian centre could not operate due to the danger, and cellphone service