Russia has intensified its assault on eastern Ukraine with one military expert predicting a “critical few weeks” for the war after the fall of Mariupol.
Ukrainian President Volodymyr Zelensky described the conditions in the Donbas, which includes Luhansk and neighbouring Donetsk province, as "hell" and said the region had been "completely destroyed" by Russia.
Russian troops bombarded the riverside city of Sievierodonetsk on Friday in what seemed to be the start of a major assault to seize the last remaining Ukrainian-held territory in Luhansk which is one of the two provinces Russia claims are independent states.
The city, and its twin Lyshchansk on the opposite bank of the Siverskiy Donets river, form the eastern part of a Ukrainian-held pocket Russia has been trying to overrun since mid-April after failing to capture the capital Kyiv.
"The Russian army has started very intensive destruction of the town of Sievierodonetsk, the intensity of shelling doubled, they are shelling residential quarters, destroying house by house," Luhansk governor Serhiy Gaidai said via his Telegram channel.
"We do not know how many people died, because it is simply impossible to go through and look at every apartment," he said.
Ukraine’s general staff said it had pushed back an offensive on Sievierodonetsk, part of what it described as major Russian operations along a stretch of the frontline.
Despite losing ground elsewhere in recent weeks, Russian forces have advanced on the Luhansk front, in what some military analysts view as a major push to achieve its scaled-down war aims of capturing territory claimed by pro-Russian rebels.
Mathieu Boulegue, an expert at London’s Chatham House think tank, said: “This will be the critical next few weeks of the conflict.
“And it depends on how effective they are at conquering Sievierodonetsk and the lands across it.”
At the same time the UK Ministry of Defence warned Russia risked more losses if it tried to move troops previously tied down in Mariupol into the battle for the Donbas too quickly without them being rested and re-equipped.
Ukrainian resistance was also stiffened on Friday when the G7 countries agreed to give £15.8 million in economic aid to Ukraine to ensure its crumbling economy did not hinder its ability to defend itself.
The IMF predicted earlier this year Ukraine’s economy is set to shrink by a third this year and next.
In Moscow, Russian Defence Minister Sergei Shoigu said the "liberation of the Luhansk People’s Republic" would be over soon.
While on Friday Russia’s defence chief said the country’s forces have taken full control of the steel plant in the devastated city of Mariupol. That would mark the end of a near three-month siege that come to symbolise Ukraine’s stubborn refusal to back down in the face of Putin’s invasion. There was no immediate confirmation from Ukraine.
In a video, the commander of the Azov Battalion, a Ukrainian unit that had defended the plant, confirmed the order to stop fighting was being implemented, and said all civilians and wounded fighters were now out.
The dead were being removed from underground tunnels and bunkers, said the commander, Denys Prokopenko: "I hope that in the near future, relatives and Ukraine will be able to bury their soldiers with honour."
Natalia Zarytska, wife of an Azovstal fighter who surrendered, said she had not heard from him since a 10-minute message exchange on Telegram two days ago. She believed he was still alive and would one day return home.
"The situation is really hard and horrible and my husband is on the way from one hell to another hell, from Azovstal steel plant to a prison, to captivity," Zarytska said in Istanbul, where she and other family members lobbied Turkey to try to help save the fighters.
The Red Cross says it has registered hundreds of Ukrainians who surrendered at the plant as prisoners of war, but has given no firm numbers.
Kyiv says it wants to arrange a prisoner swap. Moscow says the prisoners will be treated humanely, but Russian politicians have been quoted as saying some must be tried for crimes or even executed.
In other developments, President Zelensky has condemned a missile strike against a cultural centre in the Kharkiv region, describing the attack as “absolute evil”.
He posted a video online of the attack on the House of Culture in Lozova and said seven people were wounded including a child.
He said: “The occupiers have identified culture, education and humanity as their enemies.“What is in the heads of people who choose such targets?.
Russia will cut its supply of natural gas to Finland after the country applied to join Nato and refused to pay for energy in roubles.