Live updates: follow the latest news on Russia-Ukraine
Russian troops have reached the edge of Ukrainian city Severodonetsk, a regional governor has said.
“Very fierce” fighting has already begun in the city, said Luhansk Governor Serhiy Gaidai. The city has become a key objective for Russia's offensive in the Donbas region in the eastern part of Ukraine.
Shelling killed two civilians and wounded five others as Russian troops advanced into the city's south-eastern and north-eastern fringes, Mr Gaidai said on Monday.
Ukrainian forces have defended a city in ruins and their refusal to withdraw has slowed Moscow's offensive across the region.
Ukrainian President Volodymyr Zelenskyy said that about 90 per cent of the buildings had been damaged.
“More than two thirds of the city's housing stock has been completely destroyed. There is no telecommunication,” Mr Zelenskyy said in a televised speech.
“Capturing Severodonetsk is a fundamental task for the occupiers … We do all we can to hold this advance.”
Russian Foreign Minister Sergey Lavrov on Sunday said the “liberation” of the Donbas, an industrial region which includes the breakaway enclaves of Luhansk and Donetsk, was an “unconditional priority” for Moscow.
Mr Lavrov also denied reports that said President Vladimir Putin is ill, saying there were no signs pointing to any ailment.
Mr Putin's health and private life are almost never discussed in public in Russia.
“I don't think that sane people can see in this person signs of some kind of illness or ailment,” Mr Lavrov said, according to Russia's foreign ministry.
“You can watch him on screens, read and listen to his speeches [every day]. I leave it to the conscience of those who spread such rumours.”
Ukrainian forces in the Donbas region said they were on the defensive all day on Sunday. Russian forces fired on 46 communities in the Donetsk and Luhansk enclaves, killing at least three civilians, wounding two others or destroying or damaging 62 civilian buildings.
Russian shelling also continued on Sunday across several regions, including Novy Buh in Mykolaiv and Sumy.
A Ukrainian soldier on patrol in trenches near the town of Bakhmut, south-west of Severodonetsk, expressed fear that his government could be drawn into negotiating an end to the conflict that would result in Ukraine losing territory.
“You know now what I am most afraid of, now that the fighting is so intense, so tough? That we would be told: that's it, stop it, we have a ceasefire,” Dmytro, a former English language teacher, told Reuters television.
“A negotiated settlement can only happen on Ukrainian terms and at present if it happened it would be a horror.”
He said such a move could end Mr Zelenskyy's career.
EU leaders will meet on Monday and Tuesday to discuss a new sanctions package against Russia, including an oil embargo.
