Ukrainian President Volodymyr Zelenskiy has called for comprehensive peace talks with Moscow, saying Russia would otherwise need generations to recover from losses suffered during the war.

Zelenskiy said Ukraine had always offered solutions for peace and wanted meaningful and honest negotiations without delay.

“I want everyone to hear me now, especially in Moscow. The time has come for a meeting, it is time to talk,” he said in a video address released in the early hours of Saturday.

“The time has come to restore territorial integrity and justice for Ukraine.

“Otherwise, Russia’s losses will be such that it will take you several generations to recover.”

Both sides have been involved in talks for weeks with no sign of a breakthrough.

Indeed, Putin held to the hard line when he told a crowd of 80,000 at a Moscow rally that he is determined to subdue “Ukraine’s nazis”.

“We know what we need to do, how to do it and at what cost. And we will absolutely accomplish all of our plans,” Putin told the rally from a stage decked out with slogans such as “For a world without Nazism” and “For our president”.

Many of the attendees told Western reporters they were ordered to attend under pain of punishment.

The national broadcast of Putin’s speech was mysteriously cut off in mid-sentence, with Kremlin officials blaming unspecified “technical problems”.

Zelenskiy has accused Russian forces of deliberately blocking  humanitarian supplies from reaching cities under attack.

“This is a deliberate tactic … This is a war crime and they will answer for it, 100 per cent,” he said.

Plea for more and better weapons

Zelensky also called on the West to provide advanced weapons instead of “certain hunting guns” as Russia expanded its attacks to Ukraine’s far west.

Volodymyr Zelensky has warned Vladimir Putin that Russia will be the ultimate victim of the Ukraine invasion. Photo: AAP

Russian missiles were fired on Lviv near the border with Poland, striking an airport in a city basically on NATO’s doorstep where hundreds of thousands have sought refuge.

In the southern city of Mariupol, the mayor said fighting had reached the city centre, with forces engaged in fierce gun battles as hundreds of people remained trapped under the rubble of a bombed theatre.

But in the capital Kyiv, the Ukraine Army has given an upbeat assessment of its defences and said the Russian army had been stopped from getting any closer to the city’s heart.

Ukraine said it had prevented Russian troops from making any fresh advances on Friday and the Russians had problems with food, fuel and communications.

Mr Zelensky said his country needed advanced weapons and warned Western leaders they would face “moral defeat” if Ukraine did not get better military aid to help save more civilian lives.

“We still have no missile defence. We do not have enough fighter planes,” said Mr Zelensky said.

“We shall call even louder on certain Western leaders and remind them that this will be their moral defeat if Ukraine does not receive the advanced weapons that will save the lives of thousands of our people.

“Russian missiles are not going to be defeated by certain hunting guns that they are trying to sell us sometimes.”

Empty strollerss in Lviv ilustrate the children killed in Russia’s war on Ukraine. Photo: Getty

Mr Zelensky said rescue work was ongoing to save hundreds of people still believed to be trapped under the rubble of the bombed theatre in Mariupol.

Earlier, human rights ombudswoman Lyudmyla Denisova reported 130 survivors had been rescued but there was still no information on more than 1000 other people believed to be sheltering there.

Buried beneath the rubble

“There are still hundreds of Mariupol residents under the rubble. Despite the shelling, despite all the difficulties, we will continue the rescue work,” said Mr Zelensky.

Meanwhile Russian President Vladimir Putin has addressed a stadium filled with tens of thousands of people waving Russian flags and told them the “special operation” would succeed.

The event was marking the eighth anniversary of Russia’s annexation of Crimea.

“We know what we need to do, how to do it and at what cost. And we will absolutely accomplish all of our plans,” Mr Putin said, adding that, when needed, Russian soldiers “shield each other from bullets with their bodies like brothers”.

State television briefly cut away from his speech in mid-sentence but Kremlin spokesman Dmitry Peskov said later the interruption was due to a technical fault.

The BBC spoke to public servants who said they were pressured to attend the stadium gathering and students who said they had been enticed to go with the promise of a day off.

In other developments Russian negotiator Vladimir Medinsky said delegates were “halfway there” in agreeing on the issue of Ukraine’s demilitarisation.

Interfax news agency quoted Mr Medinsky as saying negotiating teams were discussing nuances of security guarantees should Ukraine no longer attempt to join the NATO military alliance.

Ukraine’s negotiator said its position was unchanged and it wanted peace negotiations to lead to a ceasefire, the withdrawal of Russian troops and security guarantees.

Ceasefire, withdrawal … security guarantees

“The statements of the Russian side are only their requesting positions,” Ukrainian negotiator Mykhailo Podolyak said on Twitter.

“All statements are intended, inter alia, to provoke tension in the media.

“Our positions are unchanged. Ceasefire, withdrawal of troops & strong security guarantees with concrete formulas.”

Russia’s invasion of Ukraine, now in its fourth week, has killed hundreds of civilians, reduced city areas to rubble and sparked a humanitarian crisis as millions flee the country.

Evheniy Nikolin and Evheniya Horho after a residential area was bombarded in Kyiv. Photo: Getty

The China card

Joe Biden and Xi Jinping have spoken on a video call about Russia’s invasion of Ukraine, and Chinese media say Mr Xi underlined that such conflicts were in no one’s interests.

Mr Biden was expected to tell Mr Xi that China would pay a steep price if it supported the invasion, a warning that comes at a time of deepening acrimony between the two countries.

The call lasted just under two hours, the White House said.

Mr Xi told Mr Biden that conflicts and confrontations such as the events in Ukraine were in the interests of no one, according to Chinese state media.

State-to-state relations cannot advance to the stage of confrontation, and conflicts and confrontations are not in the interests of anyone, Mr Xi said.

“The Ukraine crisis is something that we don’t want to see,” Mr Xi was quoted as saying.

Chinese state media said the call had been requested by the US side.

Before the call, a Chinese aircraft carrier sailed through the sensitive Taiwan Strait on Friday.

The USS Ralph Johnson, an Arleigh Burke guided missile destroyer, shadowed the carrier at least partly on its route.

China claims democratically ruled Taiwan as its own, and has over the past two years stepped up its military activity near the island to assert its sovereignty claims, alarming officials in Taipei and Washington DC.

-with AAP