Deadly strikes battered Ukraine on Monday as Russia threatened to take "full control" of major cities despite fresh talks to halt the devastating invasion.
On the 19th day of the invasion, the fourth round of talks made no breakthrough other than a planned resumption Tuesday.
Russian forces shelled the capital Kyiv while Russian-backed separatists said fragments from a shot-down Ukrainian Tochka-U missile ripped through the centre of the eastern city of Donetsk, killing 23 people.
Moscow called it a "war crime" and rebels published photos of bloody corpses strewn in the street, even as the Ukrainian army denied having fired a missile at the city.
In the neighbouring region of Lugansk, Ukrainian commander Sergiy Gaiday said the whole Ukrainian-held zone was being bombarded, including "homes, hospitals, schools, water, gas and electricity networks" as well as trains evacuating civilians.
The United Nations estimates almost 2.8 million people have fled Ukraine since Russian President Vladimir Putin launched the full-scale land and air assault on February 24, most of them to Poland, struggling to provide for the arrivals.
Outside the western Ukrainian city of Rivne, nine people died and another nine were injured on Monday when Russian forces hit a television tower, local authorities said.
Rescuers were working to free survivors trapped under the rubble in the village of Antopil, the head of the regional administration, Vitaliy Koval, said on messaging app Telegram.
As Moscow's military advanced steadily towards several major urban hubs, Russian air strikes killed at least two in Kyiv, now hemmed in on two sides and drained of more than half of its three million residents.
"They say that he is too severely burned, that I won't recognise him," sobbed Lidiya Tikhovska, 83, staring at the spot where a paramedic said the remains of her son Vitaliy lay.
"I wish Russia the same grief I feel now," she said, tears rolling down her cheeks as she clung to her grandson's elbow for support.
During its meeting with Russian representatives, Ukraine said it was demanding "peace, an immediate ceasefire and the withdrawal of Russian troops". The videoconference talks paused without a breakthrough ahead of a planned resumption on Tuesday.
"Only after this can we talk about regional relations and about political differences," Kyiv's lead negotiator Mikhailo Podolyak said in a video statement posted to Twitter.
Kremlin spokesman Dmitry Peskov told reporters that Putin had ordered his forces "to hold back on any immediate assault on large cities because the civilian losses would be large".
He added however that the defence ministry "does not rule out the possibility of putting large cities, which are already almost fully encircled, under its full control".
Russian troops not only edged closer to Kyiv but kept up their siege of the southern port city of Mariupol, where officials said nearly 2,200 people have been killed.
Russia's forces had earlier focused on eastern and southern areas of Ukraine -- home to more ethnic Russians -- but in recent days have moved to the country's centre.
In Kyiv, only the roads to the south remain open, according to the Ukrainian presidency. City authorities have set up checkpoints, and people are stockpiling food and medicine.
The north-western suburb of Bucha is held by Russian forces, along with parts of Irpin, Ukrainian soldiers told AFP. Some blocks in the once well-to-do suburb have been reduced to rubble.
The Russians are encountering resistance from the Ukrainian army to both the east and west of the capital, according to AFP journalists on the scene.
Talks between Kyiv and Moscow have yet to yield a ceasefire and Russian forces have shown no sign of easing their onslaught.
The aim was "to do everything to ensure a meeting of presidents. A meeting that I am sure people are waiting for," said President Volodymyr Zelensky.
"We see significant progress," Leonid Slutsky, a senior member of Russia's negotiating team, told state-run television network RT on Sunday.
NATO allies Turkey and Germany on Monday appealed for an immediate ceasefire in order to open humanitarian corridors for civilian evacuations.
The EU meanwhile adopted fresh sanctions against Russia. Diplomats said the oligarch, Chelsea football club owner Roman Abramovich, was among the individuals listed.
In an attack dangerously close to NATO member Poland, Russian air strikes on a Ukrainian military training ground near the border killed at least 35 people and wounded more than 130 on Sunday.
Zelensky has urged NATO to impose a no-fly zone, but the United States has ruled out any direct intervention.
President Joe Biden has warned that NATO fighting Russia "is World War III".
"If you do not close our sky, it is only a matter of time before Russian missiles fall on your territory, on NATO territory, on the homes of NATO citizens," repeated Zelensky, who is to deliver a virtual address to the US Congress on Wednesday.
A US defence official said Monday that the cruise missiles fired in the attack near the Polish border were launched from aircraft in Russian air space and that a no-fly zone would not have prevented the attack.
Washington and its EU allies have sent funds and military aid to Ukraine and imposed unprecedented economic sanctions on Russia.
In a sign Moscow may have underestimated the challenge it would face, US officials told media that Russia had asked China for military and economic aid for the war.
Beijing accused Washington of spreading lies over China's role in the Ukraine war, without directly addressing the US media reports.
The White House said US and Chinese officials meeting in Rome on Monday held a "substantial discussion" of the Russian invasion.
In an intelligence update on Sunday, Britain's defence ministry said Russia had established a naval blockade on the Black Sea coast, "effectively isolating Ukraine from international maritime trade".
Efforts continued to get help to the devastated southern city of Mariupol, which aid agencies say is facing a humanitarian catastrophe.
In a glimmer of hope for residents of the besieged city, more than 160 civilian cars were able to drive out along a humanitarian evacuation route on Monday after several failed attempts.
Heavy bombardment has left some 400,000 inhabitants in the city with no running water or heating and food running short.
Zelensky has accused Moscow of both blocking and attacking humanitarian convoys, although he said Sunday that another 125,000 people had been evacuated that way across Ukraine.
He says the Russians have lost about 12,000 troops -- although Moscow put the number at 498, in its only toll released March 2.
About 1,300 Ukrainian troops have been killed, according to Kyiv.
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