ITV News Europe Editor James Mates reports on the latest news from inside Ukraine after the first attempt at peace talks finishes
The Hague is to investigate possible war crimes, or crimes against humanity, carried out in Ukraine as Russia continues its invasion.
There have been reports of shelling in civilian areas of Ukraine.
Video from Kharkiv shows a residential area being hit by what appears to be cluster bombs, a shopping centre under fire, and the carpark of an apartment building hit.
As Russian ambassador to the UN held a press conference he was told a dozen members of his delegation were being told to leave the US, ITV News Correspondent Emma Murphy reports
The chief prosecutor of the International Criminal Court (ICC) said in a statement he plans to open an investigation "as rapidly as possible".
Prosecutor Karim Khan said it will look at alleged crimes committed before the Russian invasion last week, but added "given the expansion of the conflict in recent days" he intends the investigation "will also encompass any new alleged crimes falling within the jurisdiction of my office... on any part of the territory of Ukraine."
ITV News Correspondent Dan Rivers reports from Kharkiv, he describes 'potential war crimes happening in Europe - right before our eyes'
Ukrainian authorities did not reveal any information about the talks in Monday, but said the delegations had returned to their capitals and more could take place soon.
The negotiations were held on the border with Belarus and were the first face-to-face talks since the start of the invasion.
Ukrainian President Volodymyr Zelenskyy’s office said it would be demanding an immediate cease-fire and withdrawal of Russian troops.
How realistic is a peace deal right now? Unlikely according to ITV News Europe Editor James Mates
It was not immediately clear what President Vladimir Putin was seeking in the meeting held at a long table with the blue-and-yellow Ukrainian flag on one side and the Russian tricolour on the other.
Ukraine sent its defence minister and other top officials by helicopter to the meeting arranged "without precondition", but the Russian delegation was led by Putin's adviser on culture - an unlikely envoy for ending the war and a sign of how Moscow views the meeting.
While the talks were ongoing, Ukraine's second-largest city, Kharkiv, was shelled by Russian artillery with authorities saying 44 people had been injured and seven had died.
Numerous videos circulated on social media showed Russian armoured vehicles travelling into the city, but it is believed to still be under Ukrainian control.
Before the talks began, Mr Zelenskyy confirmed 16 Ukrainian children have been killed and another 45 injured in the days since the Kremlin launched its invasion.
Earlier, Mr Zelenskyy addressed Russian soldiers directly, telling them 4,500 Russian troops have been killed and urged them to lay down their weapons and leave.
"Don't trust your commanders, don't trust your propaganda, just save your lives," he said.
What are the latest developments in the crisis?
The International Criminal Court says it plans to open an investigation "as rapidly as possible" into possible war crimes and crimes against humanity in Ukraine.
The first round of high-stake talks between Ukraine and Russia on the border with Belarus wrapped up, with no information given other than the possibility for further talks was still open.
The Ukrainian president also said he will release Ukrainian prisoners with combat experience to defend the country.
The Russian army claimed the city of Berdyansk, a small port city on the country's southern coast that has a small naval base.
An explosion was also reported in the city of Cherkasy and a missile is understood to have hit a residential area in the city of Chernihiv, where the British MoD says "heavy fighting" continues.
The Russian military said its nuclear deterrent forces have been put on high alert in line with President Putin’s order - a move the Kremlin blamed on comments made by UK Foreign Secretary Liz Truss.
Russia's currency, the rouble, plummeted on Monday and Russia's Central Bank raised its rate from 9.5% to 20% in a desperate bid to save the economy, as the West's sanctions hit the country hard with the UK announcing more on Monday.
Russia closed its airspace to carriers from 36 nations, including European countries and Canada.
Websites of several Russian media outlets were hacked on Monday, with a message condemning Moscow’s invasion of Ukraine appearing on their main pages.
The US State Department announced it has closed the US Embassy in Belarus and is allowing non-essential staff at the American Embassy in Russia to leave the country.
Boris Johnson spoke with President Zelenskyy on Monday and with a group of Western world leaders including President Joe Biden, who all hailed the bravery of the Ukrainian people.
Russian football teams, including the national team, was suspended from all international competitions by FIFA and UEFA.
The International Olympic Committee has recommended that international sports federations and sports event organisers do not invite or allow the participation of Russian and Belarusian athletes in international competitions.
More than half a million Ukrainians have fled the country to Poland, Romania, Hungary and other European countries, while those who stayed hunkered down in makeshift bomb shelters in underground garages and subway stations, as they were advised against going out.
The UN has estimated Russia's attack could create as many as four million refugees.
A destroyed tank seen on a road near the airport in Kharkiv shows the battle for Ukraine's second largest city is "not over", reports ITV News Correspondent Dan Rivers
Across Ukraine, defenders have put up stiff resistance that appeared to slow the invasion, but a US official cautioned that far stronger Russian forces inevitably will learn and adapt their tactics as their assault goes on.
Nato's secretary-general Jens Stoltenberg Tweeted that he commended President Zelenskyy in a call "for the bravery of the people and armed forces of Ukraine", pledging that allies are "stepping up support with air-defence missiles, anti-tank weapons, as well as humanitarian and financial aid".
Listen to the ITV News podcast What You Need To Know, for the latest expert analysis on Ukraine
British Defence Secretary Ben Wallace said although the Ukrainians were putting up “a very strong fight” the reality was they were going up against “the overwhelming scale of the Russian Federation Army”.
He believes Putin’s nuclear warning is a “big attempt to distract away from his troubles in Ukraine” and is part of a "battle of rhetoric".
But Mr Wallace did not rule out Putin launching a nuclear attack and said he understood the concerns about the warning made by the Russian leader - revealing his own 12-year-old son called him worried about the step.
“This is predominantly about Putin putting it on the table just to remind people, remind the world, that he has a deterrent,” he said, adding that the West still takes the threat "very, very seriously".
The prime minister agreed that Putin's nuclear order appeared to be an attempt to divert from the fact that his efforts to re-make the post-Cold War order in Europe were failing.
Despite his pledges to help the Ukrainian community, Mr Johnson has come under criticism after announcing that immediate family members will be able to join Ukrainians settled in the UK as they flee the Russian invasion.
Home Secretary Priti Patel said an extra 100,000 Ukrainians will be allowed to "seek sanctuary" in the UK for the next 12 months, after temporarily relaxing immigration rules, but she stopped short of a full visa waiver.
The government has also said it is fast-tracking plans to tackle "dirty money" and expose foreign oligarchs who launder their wealth through the UK's property market in the wake of Russia's invasion of Ukraine.
On Monday afternoon, the United Nations held a rare emergency meeting of its General Assembly in New York to discuss the crisis - it was only the 11th time such a session has been held.
On the eve of his trip on Tuesday to Poland and Estonia, Boris Johnson said international leaders were united in agreeing that the Russian president “must fail” after his decision to send troops into the neighbouring country.
Mr Johnson is due to meet with Warsaw and Tallinn leaders and visit British troops serving in Estonia, which shares a border with Russia.
Speaking before his visit to the two eastern European members of Nato, the Prime Minister said: “Today I will visit Poland and Estonia, two countries that are acutely affected by the current crisis in Ukraine.
“We have shared values that are more important than ever to protect, as the humanitarian situation gets worse.
“Alongside all our international allies the UK will continue to bring maximum pressure to bear on Putin’s regime to ensure he feels the consequences of his actions in Ukraine.
“We speak with one voice when we say, Putin must fail.”