Foreign Secretary Liz Truss said the UK was freezing the assets of Sberbank, Russia’s largest bank, and Credit Bank of Moscow, banning all new investment in Russia and targeting eight more oligarchs.
Ahead of the announcement of the Government energy security strategy on Thursday, she said Britain would end all imports of Russian coal as well as oil by the end of the year.
The announcement coincided with a parallel move against Sberbank by the US which is also sanctioning Vladimir Putin’s two adult daughters, Mariya Putina and Katerina Tikhonova, and other members of the Russian elite.
Earlier the European Commission set out proposals for a fifth round of sanctions, including a ban on coal imports, for approval by EU ambassadors.
The moves follows an international wave of revulsion over reported atrocities committed by Russian forces in Bucha and other towns around Kyiv which have been recaptured by the Ukrainians as the Russians pull back.
Ukrainian officials said they had found the bodies of at least 410 civilians, some reported shot with their hands tied behind their backs.
There have also been reports of women being raped by Russian soldiers in front of their children.
Speaking during a visit to a hospital in Welwyn Garden City, Mr Johnson said: “I’m afraid, when you look at what’s happening in Bucha, the revelations that we are seeing from what Putin has done in Ukraine, which doesn’t look far short of genocide to me, it is no wonder people are responding in the way that they are.”
Western officials warned such atrocities may be “widespread” pointing to the “toxic information climate” in Russia with calls for the “de-nazification” of Ukraine, with former president Dmitri Medvedev, still a close ally of Mr Putin likening it to the Third Reich.
“When you combine that with a force which is failing and failing badly in an operation for which it was perhaps psychologically underprepared, it just a toxic mix,” one official said.
“The responsibility for this lies with the perpetrators of the acts but it also lies with the Russian leadership. Not only did they order the invasion, they set the tone and the context for this operation as well.”
Ms Truss said the latest UK measures amounted to “some of our toughest sanctions yet” and were “decimating Putin’s war machine”.
“Together with our allies, we are showing the Russian elite that they cannot wash their hands of the atrocities committed on Putin’s orders.
“We will not rest until Ukraine prevails,” she said.
Earlier, Ukrainian President Volodymyr Zelensky issued a renewed call for further economic meausures in a video address to both houses of the Irish parliament.
Following his impassioned appeal to the United Nations Security Council to establish Nuremberg-style tribunals to try those responsible for war crimes, he accused Russia of using hunger as a weapon of war.
“They are destroying things that are sustaining livelihoods to people,” he said.
“Why are they doing this? Because for them hunger is a weapon against us, ordinary people as an instrument of domination.”
Meanwhile, Western officials said the withdrawal of Russian forces from around the north of Kyiv appeared to be largely complete.
However they said it could be a “number of weeks” before they were ready for re-deployment in the Donbas region – part-held by pro-Russian separatists – which is Moscow’s new focus of operations.
Of the estimated 125 Russian tactical battalion groups at the start of the invasion, 29 were thought to be “combat non-effective” and had been taken out of the line due to the heavy casualties they have suffered.
Nevertheless, officials believe President Putin may be determined to achieve some sort of gains which he can hold up as a success by May 9 – the date of the annual military parade in Moscow.
“We believe May 9 is a significant date. One can only imagine there will be a desire to have an announcement of success by that period,” one official said.
“As we saw in the first phase of this campaign, when you have a political imperative which drives things in a particular way, you can end up with military disaster as a consequence.”
Nato secretary general Jens Stoltenberg said they were now expecting a “major offensive” by the Russians in the Donbas, as he warned there could be “a long haul” ahead for Ukraine.
Speaking as alliance foreign ministers gathered in Brussels, he said: “We have seen no indication that President Putin has changed his ambition to control the whole of Ukraine and also to rewrite the international order so we need to be prepared for a long haul.”