Russian air strikes killed 35 people at a military base outside Ukraine's western city of Lviv, local officials said on Sunday, in an attack that brings the conflict dangerously close to the Polish border.
Another nine people were also killed in a strike on the southern city of Mykolaiv, the regional governor said, while the capital Kyiv braced for possible encirclement by Russian forces.
In a video address posted on social media late Saturday night, President Volodymyr Zelensky was adamant that the Russians would not take Ukraine.
“The Russian invaders cannot conquer us. They do not have such strength.According to Ukrainian sources, Vladimir Putin's forces had launched a missile strike on the International Center for Peacekeeping and Security, also known as Yavoriv military complex, just before 6am this morning. Initial reports suggested the base had been targeted by eight missiles, but Maksym Kozytskyi, Governor of the region later confirmed 30 cruise missiles had been fired, killing nine people and injuring 57.
Photos emerging from the scene show the facility in ruins, with wounded service personnel being attended to by medics.
The base has previously been used to host Nato drills and up until recently has housed foreign military instructors, although its unclear if any have been caught up in the strike.
Ukrainian Defence Minister Oleksii Reznikov renewed calls for a 'no-fly zone' over the country following the attack.'Russia has attacked the International Center for Peacekeeping and Security near Lviv,' he wrote on Twitter.
'Foreign instructors work here. Information about the victims is being clarified. This is new terrorist attack on peace and security near the EU-NATO border. Action must be taken to stop this. Close the sky!'
This morning there were reports on social media that explosions could be seen and heard from the outskirts of Lviv nearly 30 miles away
The city has been a haven for refugees in recent weeks, with hundreds of thousands going through as they travelled west toward Poland and other EU countries.
During the night air raid sirens went off in the city, which is home to more than 700,000 people and has been largely spared the violence seen in other major settlements such as Kyiv, Mariupol and Kharkiv.Meanwhile an Associated Press journalist in Mariupol witnessed tanks firing on a nine-story apartment building and was with a group of hospital workers who came under sniper fire on Friday.
A worker shot in the hip survived, but conditions in the hospital were deteriorating, with electricity reserved for operating tables, and people with nowhere else to go lined the hallways.
In other developments:
Kyiv became a fortress ahead of an expected onslaught, with Russian forces now within 15 miles of the capital's centre;
Russian shelling of besieged cities including Kharkiv, Mykolaiv, Dnipro and Sumy continued as one governor said the South-Eastern city of Volnovakha has been destroyed;
Putin rebuffed a new appeal for a ceasefire but, in a glimmer of hope, negotiators discussed 'concrete' proposals for a peace deal for first time as Ukrainian President Volodymyr Zelensky said he was willing to negotiate, but would not surrender nor accept ultimatums;
Zelensky revealed 1,300 Ukrainian troops have died in the war so far, but claimed the Russian army has suffered its largest losses in decades, with an estimated 6,000 deaths;
Moscow threatened the West that any military shipments to Ukraine will be seen as 'legitimate targets', prompting fears the conflict could dramatically escalate;
Putin was urged to lift the siege of the southern city of Mariupol where up to 1,500 civilians have died;
Residents took to the streets of the occupied city of Melitopol to protest against the abduction of its mayor by Russian forces;
Intelligence sources claimed Putin may be suffering from dementia, Parkinson's disease or 'roid rage' resulting from steroid treatment for cancer.
Polish president Andrez Duda has told the BBC he fears Russia could use chemical weapons in an effort to break the deadlock.
Speaking on Sunday Morning with Sophie Raworth, he said: 'Actually, politically, he has already lost his war and internally he is not winning it', adding that if Putin uses these types of weapons Nato will have to consider its next move.
Also speaking on Sunday morning, Labour leader Sir Keir Starmer said he was focusing on the situation in Ukraine, instead of calls for Boris Johnson to resign as Prime Minister following recent scandal.
Talking to Sky News' Sophy Ridge, he said: 'I haven't changed my mind on Boris Johnson. I think he has lost the moral authority to lead. I don't think he is fit to be our Prime Minister.
'I can't force him to resign. Only Tory MPs can do that. But I have to say that just at the moment, my total focus is on the Ukraine and what we have to do in response to the Russian aggression there.
'I think everybody will understand that my focus is on that vital issue just at the moment.'
Meanwhile, Michael Gove, the Levelling Up, Housing and Communities Secretary, said more than 3,000 UK visas have been issued to fleeing Ukrainians.
Yesterday it was confirmed Russian forces have 'completely destroyed' the eastern Ukrainian town of Volnovakha following a days-long bombing campaign - but fighting continues for territory there to prevent a Russian encirclement as citizens refuse to accept Moscow's rule.
Donetsk governor Pavlo Kyrylenko confirmed the town had been destroyed late on Saturday, saying that Volnovakha 'no longer exists' after Moscow's 'war of annihilation' that has left the smouldering remains of the town 'in the hands of Russian-backed separatists'.
Images and videos posted on social media showed Russian forces, complete with the tell-tale Z markings on their vehicles, entering the burnt out town that now primarily consists of rubble.
Moscow's troops continue to use indiscriminate shelling to encircle key Ukrainian cities and are said to be bearing down on Kyiv for an 'all-out assault' in the coming days.
Satellite images taken on Saturday morning showed extensive damage to civilian infrastructure and residential buildings throughout the southern Ukrainian city of Mariupol, a private US company said.
Maxar Technologies said fires were seen in the western section of the Black Sea port city and dozens of high-rise apartment buildings had been severely damaged.
Ukrainian President Vlodymyr Zelensky has accused Russia of shooting children and said Putin's forces will only take Kyiv if they 'raze the city to the ground', with Kremlin troops inching closer to the capital and conflict raging nearby on Saturday, endangering attempted evacuations.
And Vlodymyr Zelensky has slammed the West for its inaction, saying on Saturday that he 'doesn't see any bravery from NATO' as he pleaded for more involvement from allies in peace negotiations and offered to pay for more anti-missile systems.
In response, the US made lukewarm promises of taking 'diplomatic steps' to help the Ukrainian government.