Three European prime ministers have travelled to the capital of Ukraine by train in a show of “unequivocal support”, even amid intense fighting around Kyiv and while buildings there remain ablaze after further fatal attacks.

The danger to Kyiv is escalating, with more frequent strikes on civilian and military buildings, and residents are now under curfew.

Nearby, another American was killed while working to document the invasion.

In Rivne in western Ukraine, officials said 19 people had been killed in a Russian air strike on a TV tower.

If confirmed it would be the worst attack on a civilian target so far in the northwest where Russian ground troops have yet to tread.

Meanwhile, plans are underway for US President Joe Biden to meet with NATO leaders in Europe.

Here’s the latest out of Ukraine on Wednesday morning.

Leaders show solidarity in Kyiv

That foreign leaders could attempt to visit the Ukrainian capital was a striking symbol of Ukraine’s success so far in fending off an assault that its American and European allies believe was aimed at seizing Kyiv weeks ago.

“It is our duty to be where history is forged. Because it’s not about us but about the future of our children who deserve to live in a world free from tyranny,” said Polish Prime Minister Mateusz Morawiecki, who crossed the border with Czech Prime Minister Petr Fiala and Janez Jansa of Slovenia.

Mr Morawiecki posted photographs of the meeting on social media along with the caption: “This war is the result of the cruel tyrant who attacks vulnerable civilians, bombarding cities and hospitals in Ukraine”.

He continued: “As a result, the world lost its sense of security, and innocent people die and lose their whole life’s earnings…we need to stop the tragedy that is happening in the East as soon as possible.”

The PMs shared photographs of their meeting in Kyiv. Photo: Facebook

AAP reports that Mr Fiala said the aim was “to confirm the unequivocal support of the entire European Union for the sovereignty and independence of Ukraine”.

The visit comes at a time when Ukrainian officials are playing up the hope the war could end sooner than expected, saying Russia may be coming to terms with its failure to impose a new government on Kyiv by force.

In the latest hint at compromise, President Volodymyr Zelensky said on Tuesday he was prepared to accept security guarantees that stop short of its long-term objective of the NATO alliance membership, which Russia opposes.

Ukraine understands it does not have an open door to join NATO yet, Mr Zelensky said in a video message.

“If we cannot enter through open doors, then we must co-operate with the associations with which we can, which will help us, protect us … and have separate guarantees,” he said.

A damaged building in the Ukrainian city of Irpin. Photo: Getty

The European leaders have arrived in a city still under bombardment, where about half of the 3.4 million population has fled and residents spend nights sheltering in underground stations.

Two powerful explosions rocked Kyiv before dawn on Tuesday and tracer fire lit up the night sky.

A high-rise apartment building was in flames in the morning after being struck by artillery.

At least four more people were killed in those strikes.

Firefighters tried to douse the blaze and rescue workers helped evacuate the building.

Czech and Polish officials said the prime ministers’ mission was co-ordinated with the EU and agreed by the bloc’s leaders at a summit last week.

However, some officials in Brussels were circumspect.

While every peace initiative was welcome, the trip “poses serious security risks,” one EU official told AAP.

“Some leaders might also wonder: will this jeopardise or will this improve conditions for negotiations with the Russians. It remains to be seen, of course. It’s a fine line.”

One of Mr Zelensky’s top aides said the war would be over by May, or even end within weeks, as Russia had run out of fresh troops.

“We are at a fork in the road now,” Oleksiy Arestovich said in a video.

He said he expected either a peace deal within one or two weeks or another Russian attempt with new reinforcements, which could prolong the conflict for another month.

“I think that no later than in May, early May, we should have a peace agreement, maybe much earlier: we will see,” Mr Arestovich said.

More reporters killed while filming the war

A cameraman with US broadcaster Fox News is dead after coming under fire near Kyiv.

As The New Daily reported on Tuesday, correspondent Benjamin Hall was wounded while working in Ukraine.

Fox has now released details and confirmed that Mr Hall’s colleagues did not survive. They were Pierre Zakrewski, 55 and 24-year-old Oleksandra Kuvshinova.

The network said the journalists were travelling near Horenka on Monday when their vehicle came under fire.

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Mr Zakrewski had been working in Ukraine since February, Fox News said.

He had previously covered conflicts in Afghanistan, Iraq and Syria for the broadcaster.

“He was profoundly committed to telling the story and his bravery, professionalism and work ethic were renowned among journalists at every media outlet,” a Fox News statement read.

“He was wildly popular – everyone in the media industry who has covered a foreign story knew and respected Pierre.”

Fox senior field producer Yonat Friling said Ms Kuvshinova had been working with the team for the past month and “did a brilliant job”.

“We have lost a beautiful brave woman” Ms Friling said. “She loved music and she was funny and kind.”

Mr Hall remains in hospital.

The deaths come days after Time correspondent Brent Renaud was killed while covering the war.

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Russian journalist in court for opposing war

A Russian state television journalist has appeared before a court after she staged a protest against the Ukraine war live on air.

Russian media report that Marina Ovsyannikova, an editor at the state-controlled Channel One, has been charged with organising an unauthorised public event.

In a video shared on social media, she had called on Russians to “stop all the madness” and oppose the war.

“I’m ashamed that I allowed myself to tell lies from the television screen,” the journalist had said of her work.

“Ashamed that I allowed Russians to be turned into zombies.

“We just silently watched this inhumane regime.”

The journalist had also held up a “no war” sign behind a TV anchor.

“Stop the war, don’t believe propaganda, they’re lying to you,” the poster read.

• Related: UN urges no reprisals against anti-war journalist

She has been fined 30,000-rouble fine ($A393) and could face further punishment.

Marina Ovsyannikova, ran behind the presenter on state TV’s Channel One. Photo: YouTube

Initially, supporters feared that the editor could be convicted of defaming the Russian army under a controversial new law.

This would carry with it up to 15 years in prison.

Outside the court, the journalist thanked supporters and explained how she had endured a sleepless two days including 14 hours of interrogation.

“This has been a very complicated time in my life,” Ms Ovsyannikova said, adding that she had been denied access to a lawyer.

“It was my anti-war decision. I made this decision by myself because I don’t like Russia starting this invasion. It was really terrible.”

Joe Biden will meet with NATO leaders in Belgium

American President Joe Biden will travel to Europe next week for face-to-face talks with leaders about the Russian invasion of Ukraine, White House press secretary Jen Psaki said.

The New York Times wrote that Mr Biden will meet with NATO and European leaders in Belgium’s capital, Brussels, on March 24.

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The trip follows on Vice President Kamala Harris’ visit to eastern flank NATO countries of Poland and Romania last week to discuss with leaders the growing refugee crisis in eastern Europe sparked by the Russian invasion and to underscore the US support for NATO allies.

Meanwhile, Russia has also announced on Wednesday that it will impose sanctions on Americans including Mr Biden, his son Hunter and former presidential candidate Hilary Clinton. The sanctions include a ban on the high-profile Americans entering Russia.

White House press secretary Jen Psaki laughed off questions about those sanctions, explaining “none of us are planning tourist trips to Russia”.

-with AAP