Moscow has demanded surrender in Mariupol as Russia’s defence ministry claimed it had cleared Ukrainian forces from the besieged city’s entire urban area.

But Ukraine earlier claimed its troops were still holding out in the ruins of the port city, the scene of the war’s heaviest attacks and worst humanitarian catastrophe.

Russian forces have been trying for several weeks to take the port, which is strategically placed on the Sea of Azov, a body of water to the northeast of the Black Sea.

“The entire urban area of ​​Mariupol has been completely cleared … remnants of the Ukrainian group are currently completely blockaded on the territory of the Azovstal metallurgical plant,” the Russian ministry said.

“Their only chance to save their lives is to voluntarily lay down their arms and surrender.”

There was no immediate reaction from Kyiv but earlier President Volodymyr Zelensky said Ukraine would not trade any of its territory and would walk away from talks with Russia if its defenders in Mariupol were eliminated.

“I want to say that the elimination of our military, our guys, will put an end to all negotiations,” Mr Zelensky said.

The Ukrainian military in the ruins of a shopping centre in Kharkiv. Photo: Getty

Meanwhile Moscow has followed through with its threat of more attacks after the sinking of its prized warship as intelligence reports warn of Vladimir Putin’s increasingly unpredictable behaviour.

Warplanes have bombed Lviv, the largest city in the west, and missiles struck the capital Kyiv and the city of Kharkiv, in the northeast, after Russia’s flagship Moskva navy vessel was sunk.

Mr Zelensky had earlier told CNN that the world should be prepared for the possibility that Russia’s president could unleash tactical nuclear weapons.

CIA director William Burns said nuclear strikes should not be taken lightly given Russia’s failures so far in Ukraine and how Mr Putin would react.

“Given the potential desperation of President Putin and the Russian leadership, given the setbacks that they’ve faced so far, militarily, none of us can take lightly the threat posed by a potential resort to tactical nuclear weapons or low-yield nuclear weapons,” Mr Burns in a speech at Georgia Tech university in Atlanta.

In the latest developments in Ukraine, Moscow said its planes had struck a tank repair factory in Kyiv and the city’s mayor said at least one person had died and medics were fighting to save others.

Ukraine’s military said Russian warplanes that took off from Belarus had also fired missiles at the Lviv region near the Polish border, where four cruise missiles were shot down by Ukrainian air defences.

The governor of Kharkiv province in the east said at least one person had died and 18 were injured in a missile strike. In Mykolaiv, a city close to the southern front, Russia said it had struck a military vehicle repair factory.

Homes in Kyiv’s outer suburbs have been flattened. Photo: Getty

In Mariupol, Ukraine’s defence is concentrated around Azovstal, another huge steel works that has yet to yield.

If Mariupol falls it would be Russia’s biggest prize of the war so far. It is the main port of the Donbas, a region of two provinces in the southeast which Moscow demands be fully ceded to separatists.

The owner of both of Mariupol’s giant steel factories, Ukraine’s richest man Rinat Akhmetov, vowed to rebuild the city.

“Mariupol is a global tragedy and a global example of heroism. For me, Mariupol has been and will always be a Ukrainian city,” Mr Akhmetov told Reuters.

Ukraine says it has so far held off Russian advances elsewhere in the Donbas.

Russia bans Boris Johnson

The UK prime minister and other British cabinet ministers have been placed on a Kremlin blacklist and banned from entering Russia in response to sanctions against the country, reports suggest.

The UK prime minister, Foreign Secretary Liz Truss, Defence Secretary Ben Wallace, Justice Secretary Dominic Raab and former PM Theresa May are believed to be among those on the list, according to the Russian news agency Tass.

Russia’s foreign ministry said in a statement the move was due to the “unprecedented hostile actions of the British Government, expressed, in particular, in the imposition of sanctions against top officials” in Russia.

I updated my friend @ZelenskyyUa this afternoon on further military aid we will provide to Ukraine in the coming days.

The UK will stop at nothing to ensure Ukrainians have the resources they need to defend their country from the ongoing Russian onslaught. #StandWithUkraine️

— Boris Johnson (@BorisJohnson) April 16, 2022

In the UK, a former cabinet minister said the Homes for Ukraine scheme where households can take in those fleeing the war was “bumpy” and visas were taking too long to be processed.

Robert Jenrick, who was previously communities secretary, revealed his family was housing a Ukrainian mother and her two children.

He is among the first MPs to have managed to get a Ukrainian family to the UK, with Tory North Norfolk MP Duncan Baker announcing earlier this month that he had welcomed a mother and her son.

But Mr Jenrick said the process by which Maria, 40, and her two children, Bohdan, 15, and Khrystyna, 11, had got to the UK was “traumatic”. Their father has stayed in Ukraine to fight in the war.

Environment Minister Victoria Prentis took in a 25-year-old Ukrainian refugee last month under a separate visitor visa scheme, while other MPs and ministers have said they have applied to host families.

Mr Jenrick told the Telegraph’s Chopper’s Politics podcast: “It has been a very difficult experience for them. Even the experience of coming here was traumatic.

“They spent seven hours queuing at the Polish border before they were able to finally leave Ukraine, catch the flight to the UK, and the experiences which they’ve had and their relatives have had in different parts of the country over the last two or three months are really harrowing.”

On the process, he said: “Truth be told it has been a bumpy start to the scheme. It’s taken too long to get visas, for us it took about three weeks to get all three visas approved.”

Some 94,700 applications have been received and 56,500 visas had been granted by Thursday, the government said.

-with AAP