An attack on a kindergarten in Ukraine was a “false flag operation designed to discredit the Ukrainians”, Boris Johnson said today.
The Prime Minister hit out at Russia - and warned “we fear very much that that is a thing we will see more of over the next few days”.
It comes after the UK, US and NATO all warned Moscow is trying to stage a false flag “pretext” for the invasion of Ukraine, despite claiming it is withdrawing troops near the border.
Ukraine's President Volodymyr Zelenskiy said pro-Russian forces had shelled a kindergarten, in what he called a "big provocation".
Video footage released by Ukrainian police showed a hole through a brick wall in a room scattered with debris and children's toys. Separate images showed emergency workers escorting small children and teachers from a building.
The Kremlin, in return, said Moscow was "seriously concerned" about reports of an escalation after the separatists accused government forces of opening fire on their territory four times in the past 24 hours.
A Reuters photographer in the town of Kadiivka, in Ukraine's rebel-held Luhansk region, heard the sound of some artillery fire, but was not able to determine the details of the incident.
Speaking on a visit to RAF Waddington in Lincolnshire, Mr Johnson said: "I wish I could give everybody better news about this, but I have to tell you that the picture is continuing to be very grim.
"Today, as I'm sure you've already picked up, a kindergarten was shelled in what we are taking to be - well, we know - was a false flag operation designed to discredit the Ukrainians, designed to create a pretext, a spurious provocation for Russian action.
"We fear very much that that is the kind of thing we will see more of over the next few days.
"What we are doing is making that we do everything to strengthen the package of sanctions that will follow immediately should there be a Russian invasion."
Mr Johnson added: "We are strengthening the eastern frontier of Nato and I'll be going to the European Security Conference in Munich a little bit later on over the weekend to talk about what we are going to do to unify the West."
Asked if he was having to rush forward the ban on tier one visas because of an influx in applications, and if it was a sign of a crackdown on Russian money in the UK, the PM said: "We address all the issues we can, as fast as we can.
"We have already some very tough laws on money laundering, on people laundering ill-gotten gains here in the UK.
"But, clearly, it's time to bring in some tough sanctions against the Russian regime, against big Russian companies - organisations of strategic importance.
"And also making sure we ... stop the raising of funds by Russian companies on London financial markets - that's a very, very tough sanction that we'll be bringing in."
Earlier, NATO Secretary General Jens Stoltenberg said Moscow is attempting “false flag operations” after reports emerged of shelling in the eastern Ukrainian region of the Donbass.
Speaking after two days of talks among the 30-member group’s defence ministers, he added: "We cannot accept a return to the age of spheres of influence where big powers bully, intimidate or dictate to others.”
An estimated 130,000 Russian forces remain stationed on Ukraine’s borders amid ongoing fears the Kremlin could order an assault.
An invasion could be launched “with very little or no warning”, said Mr Stoltenberg.
It comes after the UK’s Armed Forces minister warned a Russian invasion of Ukraine is “very, very imminent if not inevitable”.
US intelligence, backed by the UK, says thousands more Russian troops have been moved near the border despite Kremlin claims they were withdrawing.
Mr Stoltenberg told a press conference at NATO HQ in Brussels: “We are concerned that Russia is trying to stage a pretext for an armed attack against Ukraine.
“It is still no clarity, no certainty about Russian intentions. We don’t know what will happen.
“But we do know is that Russia has amassed the biggest force we’ve seen in Europe for decades, in and around Ukraine.
“And we also know there are many Russian intelligence officers operating in Ukraine… and we’ve seen attempts to stage a pretext, false flag operations to provide an excuse for invading Ukraine.”
He called on Russia to "continue to talk" and called for "dialogue and de-escalation".
The Kremlin said on Thursday it was deeply concerned with the flare-up in violence in eastern Ukraine and hoped that the West would use its influence on Kyiv to prevent further escalation.
Kremlin spokesman Dmitry Peskov said Moscow was closely watching the situation in Ukraine's rebel-controlled Donbass region.
But Foreign Secretary Liz Truss tweeted: “Reports of alleged abnormal military activity by Ukraine in Donbas are a blatant attempt by the Russian government to fabricate pretexts for invasion.
“This is straight out of the Kremlin playbook.”
In a speech in Ukraine on Thursday, Ms Truss said: "We have been warning about the likelihood of a false flag operation. That is what we are seeing taking place.
"We are very clear the aggressor in this situation is Russia. We will continue to call out false flag operations.
"We will continue to call out their cyber attacks, and their attempts to undermine Ukraine which is a democratic sovereign country which Russia agreed to respect in various agreements."
Ms Truss said the UK stood "shoulder to shoulder" with Ukraine and warned the crisis was a "litmus test" for the West.
She said: "If we hang back, that would only embolden the bullies in their campaign against sovereignty and the right of self-determination.
"This is a litmus test for the West."
Later she tweeted that she was "very concerned about reports today of increased Russian aggression: over 7,000 extra troops near the Ukraine border and an attack by pro-Russian troops on a kindergarten in Ukraine”.
She added: "The UK calls on Russia to withdraw its troops - there is still time for diplomacy and de-escalation."
Armed Forces minister James Heappey said war was not necessarily inevitable, but he was “very worried” by fresh images showing a new bridge and a large field hospital being built near the border.
He told ITV's Good Morning Britain: "Formations are shaking out into their attack positions.
"So it could happen today, tomorrow, it could happen next Wednesday, it could happen in two weeks’ time.
“But the fact is that it is very, very imminent - if not inevitable.
“And that is why diplomacy needs to continue at top speed in order to try and avert what could be utterly catastrophic."
Mr Stoltenberg added today: “The fact you’re putting a battle tank on a train and moving it in some direction doesn’t prove withdrawal of troops.
“It has to be a meaningful withdrawal, a meaningful de-escalation. That is what we’re waiting for. So far we’ve not seen that, but of course this can change.”
Ms Truss, who travelled to Kyiv today, earlier warned the crisis could go on for months.
“There is currently no evidence the Russians are withdrawing from border regions near Ukraine,” she wrote in the Telegraph.
“Russia could drag this out much longer in a brazen ploy to spend weeks more - if not months - subverting Ukraine and challenging Western unity.”
NATO defence ministers continued crisis talks this morning at the alliance’s headquarters in Brussels.
Ukraine's Ambassador to the UK Vadym Prystaiko vowed to plough on with attempts to join NATO. "At least until NATO is here, we will try to get into the alliance,” he said.
One of Russia’s top envoys accused the West of “hysteria” over fears of an invasion. Russia's Deputy UN Ambassador Dmitry Polyanskiy told ITV : "This is a very ridiculous situation, there has been hysteria, even hype, fanned for several weeks by our Western colleagues.
“They convinced each other and the whole world that Russia was about to invade, they were even naming concrete dates.
“So it happened in their minds, in their heads - we're not responsible for what's happening in their minds.”
Meanwhile, so-called "golden visas" for wealthy foreign investors are expected to be scrapped by the Government amid concerns over links between Russia and the UK.
Those eligible for the tier one investor visa, launched in 2008, must have at least £2 million in investment funds and have a UK bank account.
It has been under review due to repeated concerns that the system could be exploited because not enough background checks are made on applicants.
Sources confirmed the scheme will be abandoned in an announcement to be made next week.
Lib Dem Foreign Affairs Spokesperson Layla Moran said: “The Conservatives have turned a blind eye to Russian interference in this country for years and had an open door policy to Kremlin cronies.
“Cancelling the scheme is long overdue, it shouldn't have taken the threat of a defeat in Parliament to finally get this Government to act.”
US Secretary of State Antony Blinken told the United Nations Security Council he believed Russia plans to "manufacture a pretext" for an assault.
He said: "We don't know exactly the form it will take.
“It could be a fabricated so-called terrorist bombing inside Russia; the invented discovery of a mass grave; a staged drone strike against civilians; or a fake, even a real attack using chemical weapons.
"Russia may describe this event as ethnic cleansing or a genocide, making a mockery of a concept that we in this chamber do not take lightly."
President Joe Biden dispatched Mr Blinken to New York to brief envoys as the Ukrainian crisis deepened.
His appearance at the Security Council during a tense international standoff echoed a presentation by his predecessor, Colin Powell, in 2003 in the run-up to the US-led invasion of Iraq.
Mr Powell infamously outlined American evidence of Iraqi weapons of mass destruction, which turned out not to exist.
The current Secretary of State appeared to recognise comparisons might be drawn 19 years on.
Mr Blinken said: “I am mindful that some have called into question my information, recalling previous incidences where intelligence ultimately did not bear out.
“But let me be clear - I am here today not to start a war but to prevent one.
“The information I have presented here is validated by what we have seen unfolding in plain sight before our eyes for months.”
