The city of Sievierodonetsk in eastern Ukraine has not yet been blocked off by Russian troops, but they control about 80% of the area and have destroyed all three bridges leading out of it, an official said.
"There is still an opportunity for the evacuation of the wounded, communication with the Ukrainian military and local residents," Luhansk regional governor Serhiy Haidai told the Associated Press.
He acknowledged that Ukrainian forces have been pushed out to the industrial outskirts of the city because of "the scorched earth method and heavy artillery the Russians are using".
About 12,000 people remain in Sievierodonetsk, a city with a pre-war population of 100,000. More than 500 civilians are sheltering in the Azot chemical plant, which is being relentlessly pounded by the Russians, according to Mr Haidai.
The update from the MoD acknowledges that most of the area is now controlled by Russian forces, with the MoD’s intelligence update reading: “After more than a month of heavy fighting, Russian forces now control the majority of Sieverodonetsk. Russia’s urban warfare tactics, which are reliant on heavy use of artillery, have generated extensive collateral damage throughout the city.
"Elements of Ukrainian Armed Forces, along with several hundred civilians, are sheltering in underground bunkers in the Azot Chemical Plant, in the city’s industrial zone.
"Russian forces will likely be fixed in and around Azot whilst Ukrainian fighters can survive underground. This will likely temporarily prevent Russia from re-tasking these units for missions elsewhere.
"It is highly unlikely that Russia anticipated such robust opposition, or such slow, attritional conflict during its original planning for the invasion.”
Russian forces in the last few weeks have pressed hard to capture Ukraine's eastern industrial Donbas area, which borders Russia and is made up of the regions of Luhansk and Donetsk.
"The situation is difficult," Ukrainian President Volodymyr Zelesnky said in a news conference with Danish media. "Our task is to fight back."
Nato secretary-general Jens Stoltenberg said further artillery support for Ukraine will be discussed by members on Wednesday, while Russia indicated it would be willing to consider a UK appeal over the fate of two Britons sentenced to death.