The British military believes Russia wants to take the port city of Mariupol and its vast steel mill before its marks Victory Day on Monday.
The British Defense Ministry made the comment in a daily intelligence briefing it makes on Twitter.
The Azovstal steelworks in Mariupol has been the scene of weeks of fighting. It has a vast network of underground bomb shelters shielding fighters and civilians from Russian bombardment, though the site has been repeatedly struck by high-explosive bombs.
The British military said: “The renewed effort by Russia to secure Azovstal and complete the capture of Mariupol is likely linked to the upcoming 9 May Victory Day commemorations and Putin’s desire to have a symbolic success in Ukraine.”
It added: “This effort has come at personnel, equipment and munitions cost to Russia. Whilst Ukrainian resistance continues in Azovstal, Russian losses will continue to build and frustrate their operational plans in southern Donbas.”
Victory Day marks the Soviet Union’s victory over Nazi Germany in World War II.