The slim hope that ongoing peace talks between Russia and Ukraine can end the slaughter appear to have been dashed by the renewed ferocity of assaults by invaders and defenders alike.

The faltering negotiations came as Russia pounded areas in the east of the country and US lawmakers vowed a massive new weapons package to assist the Kyiv government’s resistance.

Russian Foreign Minister Sergei Lavrov, in remarks published early on Saturday, said lifting Western sanctions on Russia was part of the peace negotiations, which he said were “difficult” but continue daily by video link.

Ukraine president Volodymyr Zelensky told Polish journalists that chances were high that the talks, which have not been held in person for a month, would end because of Russia’s “playbook on murdering people,” the Interfax news agency said.

Ukraine accuses Russian troops of atrocities in areas near the capital, Kyiv, that they had occupied. Moscow denies the claims.

After failing to capture the capital in the nine-week assault that has turned cities to rubble, killed thousands and forced five million Ukrainians to flee abroad, Moscow is now focusing on the east and south.

Russian forces captured Ukraine’s southern city of Kherson and mostly occupied the southeastern port city of Mariupol, where the United Nations is making efforts to evacuate civilians and fighters holed up in a large steel plant.

Lavrov told China’s official Xinhua news agency that 1.02 million people had been evacuated to Russia from Ukraine since the invasion began on February 24. Ukraine says thousands have been taken to Russia against their will.

Reuters could not independently verify the claims of either side.

Lavrov said the evacuees included 120,000 foreigners and people from Russian-backed breakaway regions of Ukraine – the so-called Donetsk and Luhansk people’s republics that Russia recognised as independent just before President Vladimir Putin announced the invasion.

Moscow calls the war a “special military operation” to disarm and “denazify” Ukraine, defend Russian-speaking people from persecution and prevent the United States from using the country to threaten Russia.

Ukraine dismisses Putin’s claims of persecution and says it is fighting an unprovoked land grab to fully capture Donetsk and Luhansk, which form the Donbas region.

Refugees evacuate Mykolaiv, a port city that has experienced frequent shelling and air strikes even as Russia turns to Donbas. Photo: Getty

Britain and the United States have voiced support for Ukraine in the peace talks but say it is vital to keep arming Kyiv. On Thursday, US President Joe Biden asked Congress for $US33 billion ($A47 billion) in new aid, more than $US20 billion ($A28 billion) of it in weapons.

Ukraine acknowledges losing control of some eastern towns and villages but says Moscow’s gains have come at a heavy cost to a force already worn down from its defeat near the capital.

“We have serious losses but the Russians’ losses are much, much bigger,” Ukrainian presidential adviser Oleksiy Arestovych said, without elaborating. “They have colossal losses.”

Russia was pounding the entire Donetsk front line with rockets, artillery, mortar bombs and aircraft in part to stop Ukrainian troops from regrouping, Ukrainian officials said.

Ukraine’s military said Russia was preparing for offensives in the areas of Lyman in Donetsk and Sievierodonetsk and Popasna in Luhansk. In the south, it said, Russia was “continuing to regroup, increase fire effectiveness and improve position”.

Lamenting the destruction in Mariupol. Photo: Getty

Russia’s defence ministry said its forces had struck Ukrainian weapons storage sites, platoon strongholds, artillery positions and drones. Russia said a diesel submarine in the Black Sea had struck military targets with Kalibr cruise missiles, the first report of such strikes from a submarine.

Submarine attacks

Russia said its high precision long-range missiles had destroyed the production facilities of a rocket plant in Kyiv.

Ukraine says that attack Thursday struck a residential building, injuring civilians and killing a producer with US-backed Radio Free Europe/Radio Liberty.

The body of the producer, Vira Hyrych, was found in the building’s rubble, the broadcaster said.

Kyiv missile attack

Kyiv’s mayor Mayor Vitali Klitschko says rescue workers have recovered a corpse from the rubble of a building in the capital that was hit by a Russian missile while Mr Guterres was visiting.

Ukrainian Defence Minister Oleksiy Reznikov called it “an attack on the security of the Secretary General and on world security”.

At least four other people were wounded in the missile strike which blew out windows and scattered rubble across the streets.

I was moved by the resilience and bravery of the people of Ukraine. My message to them is simple: We will not give up.

The @UN will redouble its efforts to save lives and reduce human suffering. In this war, as in all wars, the civilians always pay the highest price. pic.twitter.com/dd1OsyzAOb

— António Guterres (@antonioguterres) April 29, 2022

Russia said its missiles destroyed the production facilities of a space-rocket plant.

Elsewhere in the capital, normal life has largely returned after weeks in which residents were forced to shelter in metro stations from bombardment.

The front line, which come right to the outskirts of Kyiv in March, is now hundreds of miles away.

But Russia can still hit the city with long range missiles as it did on Thursday.

-with AAP