The UK government on Friday ordered all assets of President Vladimir Putin and his Foreign Minister Sergei Lavrov frozen and banned oligarch jets from its airspace over Russia's invasion of Ukraine.
The Treasury issued a financial sanctions notice against the two men, adding them to a list of Russian oligarchs who have already had their property and bank accounts in the UK frozen.
British Prime Minister Boris Johnson earlier told his NATO partners that he was planning "imminent" sanctions against Putin and Lavrov.
British Transport Secretary Grant Shapps also announced an immediate ban on Russian private jets from UK airspace in response to the bloody invasion which started on Thursday.
"I've strengthened our ban in the UK so that no Russian private jet can fly in UK airspace, or touchdown –- effective immediately," Shapps tweeted.
"Putin's actions are unlawful and anyone benefitting from Russia's aggression in Ukraine is not welcome here," he said, having already banned national carrier Aeroflot.
The UK is a favourite destination for Russian oligarchs and their families and has been criticised for not doing enough to prevent the flow of their money into the country.
Johnson told his NATO counterparts that Russia's invasion of Ukraine was a "catastrophe" and the Kremlin chief was "engaging in a revanchist mission to overturn post-Cold War order".
Warning that Putin "may not stop there" and calling the situation a "Euro-Atlantic crisis with global consequences", he urged leaders to cut Russia off from the SWIFT international bank transfer system "to inflict maximum pain".
Johnson's comments ratchet up British action this week against Russian interests including banks, businesses and billionaires, though some lawmakers and experts have said the UK is not going far enough.
The White House said it would also slap sanctions on Putin and Lavrov following a similar move by the European Union.
- 'No British troops' -
Even earlier in the day, Britain and nine other northern European defence allies from the Joint Expeditionary Force (JEF) agreed in a call that further sanctions were needed on Russia.
"The leaders agreed that more sanctions were needed, including focusing on President Putin's inner circle, building on the measures that had already been agreed," Johnson's office said after the meeting.
The JEF, set up in 2012, is made up of NATO members Denmark, Estonia, Iceland, Latvia, Lithuania, the Netherlands, Norway and the United Kingdom, and non-members Finland and Sweden.
It is focused on security in the "High North" region around the Arctic, the North Atlantic and the Baltic Sea area.
At a meeting of its defence ministers on Tuesday, they announced upcoming manoeuvres in the Baltic Sea to demonstrate "freedom of movement" in the strategic zone.
Johnson pledged "further UK support to Ukraine" in a phone call with President Volodymyr Zelensky on Friday morning, as Russian forces closed in on the capital, Kyiv.
Britain has said it is ready to provide Ukraine with additional military support including lethal defensive weapons, but Defence Secretary Ben Wallace ruled out sending troops.
He told BBC television that Britain would "hold the line in NATO", adding: "I'm not putting British troops directly to fight Russian troops.
"That would trigger a European war because we are a NATO country, and Russia would therefore be attacking NATO."
Johnson praised "the bravery and heroism of the Ukrainian people in standing up to Russia's campaign of violence", according to Downing Street.