NATO allies have been warned that they could soon be targeted by Russian missiles as Ukrainians hope fresh diplomatic talks with Moscow might open the way for more civilians to evacuate.

Overnight on Sunday, Russian forces fired artillery on suburbs northwest of Kyiv, a major political and strategic target for the invasion, as well as points east of the city, regional administration chief Oleksiy Kuleba said on Ukrainian television.

A town councillor for Brovary, east of Kyiv, was killed in fighting there and shells fell on the towns of Irpen, Bucha and Hostomel, which have seen some of the worst fighting in Russia’s stalled attempt to take the capital, Kuleba said.

Artillery hit a nine-storey apartment building in a northern district of the city early on Monday morning, destroying apartments on several floors and igniting a fire. The state emergency agency, which released images of the smoking building, said it had no immediate reports of casualties.

It comes amid reports that Russia has asked China for military and economic support since launching its invasion last month. US officials told CNN that Putin has requested military equipment and financial assistance and that China had responded, thought it was not clear how.

The spokesperson for the Chinese embassy in the US, Liu Pengyu, responded: “I've never heard of that."

Meanwhile, the general staff of Ukraine’s armed forces said on Monday morning that Russian troops have not made major advances over the past 24 hours, despite expanding strikes to the west.

In one such attack, Russian missiles pounded a military base in western Ukraine on Sunday, killing 35 people in an attack on a facility that served as a crucial hub for co-operation between Ukraine and the Nato countries supporting its defence.

It raised the possibility the alliance could be drawn into the fight. The attack was also heavy with symbolism in a conflict that has revived old Cold War rivalries and threatened to rewrite the current global security order.

Ukrainian President Volodymyr Zelensky called it a “black day” and again urged Nato leaders to establish a no-fly zone over the country, a plea the West has said could escalate the war to a nuclear confrontation.

“If you do not close our sky, it is only a matter of time before Russian missiles fall on your territory … Nato territory … On the homes of citizens of Nato countries,” Zelensky said, urging Russian president Vladimir Putin to meet with him directly, a request that has gone unanswered by the Kremlin.

A fourth round of talks is expected on Monday between Ukrainian and Russian officials via video conference to discuss getting aid to cities and towns under fire, among other issues, Ukrainian presidential aide Mykhailo Podolyak said.

The talks will involve the same higher-level officials who met earlier in Belarus, aimed at “assessing preliminary results” of talks so far, Podolyak said. Previous talks have not led to major breakthroughs or a solution for getting aid or evacuation convoys to the desperate, strategic city of Mariupol.

In Mariupol, it was confirmed that the pregnant woman who was pictured being stretchered from the ruins of a shelled maternity hospital last week has died, along with her baby.

In video and photos shot last Wednesday by Associated Press journalists after the attack on the hospital, the woman was seen stroking her bloodied lower abdomen as rescuers rushed her through the rubble in the besieged city of Mariupol.

The woman was rushed to another hospital, closer to the frontline, but doctors were unable to keep her alive. Medics delivered the baby via caesarean section, but it showed “no signs of life”, Surgeon Timur Marin said. They then began work on the mother. “More than 30 minutes of resuscitation of the mother didn’t produce results,” Mr Marin said on Saturday. “Both died.”

In the US, president Joe Biden has dispatched his national security adviser to Rome to meet with a Chinese official over worries Beijing is amplifying Russian disinformation and may help Moscow evade Western economic sanctions.

The UN has recorded at least 596 civilian deaths, though it believes the true toll is much higher, and Ukraine’s prosecutor general’s office said at least 85 children are among them. Millions more people have fled their homes amid the largest land conflict in Europe since the Second World War.

Since their invasion more than two weeks ago, Russian forces have struggled in their advance across Ukraine, in the face of stiffer than expected resistance, bolstered by Western weapons support. Instead, Russian forces have besieged several cities and pummelled them with strikes, hitting two dozen medical facilities and creating a series of humanitarian crises.

That fight expanded on Sunday to the sprawling facility at Yavoriv, which has long been used to train Ukrainian soldiers, often with instructors from the United States and other countries in the Western alliance. More than 30 Russian cruise missiles targeted the site. In addition to the fatalities, the Ukrainian Defence Ministry said 134 people were wounded in the attack.

The base is less than 15 miles from the Polish border and appears to be the westernmost target struck during Russia’s 18-day invasion. It has hosted Nato training drills, making it a potent symbol of Russia’s longstanding fears that the expansion of the 30-member Western military alliance to include former Soviet states threatens its security — something Nato denies. Still, the perceived threat from Nato is central to Moscow’s justifications for the war, and it has demanded Ukraine drop its ambitions to join the alliance.

Ina Padi, a 40-year-old Ukrainian who crossed the border with her family, was taking shelter at a fire station in Wielkie Oczy, Poland, when she was awakened by blasts on Sunday morning that shook her windows.

“I understood in that moment, even if we are free of it, (the war) is still coming after us,” she said.

Russian fighters also fired at the airport in the western city of Ivano-Frankivsk, which is 94 miles north of Romania and 155 miles from Hungary, two other Nato allies.

Nato said on Sunday it currently does not have any personnel in Ukraine, though the United States has increased the number of US troops deployed to Poland. White House national security adviser Jake Sullivan said the West would respond if Russia’s strikes travel outside Ukraine and hit any Nato members, even accidentally.

Ukrainian and European leaders have pushed with limited success for Russia to grant safe passage to civilians trapped by fighting. Ukrainian authorities said on Sunday that more than 10 humanitarian corridors were set to open, including from the besieged port city of Mariupol. But such promises have repeatedly crumbled, and there was no word late on Sunday on whether people were able to use the evacuation routes.

The International Committee of the Red Cross said suffering in Mariupol was “simply immense” and that hundreds of thousands of people faced extreme shortages of food, water and medicine.

“Dead bodies, of civilians and combatants, remain trapped under the rubble or lying in the open where they fell,” the Red Cross said in a statement. “Life-changing injuries and chronic, debilitating conditions cannot be treated.”

The fight for Mariupol is crucial because its capture could help Russia establish a land corridor to Crimea, which it seized from Ukraine in 2014.