Boris Johnson has issued a direct message to the Russian people by posting a video on social media as he called for the crisis to come to an end.
In Russian the Prime Minister told countrymen: "I do not believe this war is in your name."
He described the scenes in Ukraine as "nothing short of a tragedy" and said the UK stood in solidarity with citizens their in the face of an "unjustifiable assault on their homeland".
But he said the invasion of Ukraine was also a tragedy for Russia as Vladimir Putin 's actions were leading to "complete isolation" of the country from the international community, as well as economic burden and needless lives lost.
Mr Johnson announced earlier that the UK will introduce personal sanctions against the Russian President and his foreign minister Sergei Lavrov "imminently".
The Prime Minister told Nato leaders in a virtual meeting on Friday that the UK would echo measures announced by the EU to target the Russian leader.
President Joe Biden later announced that the US was freezing the assets of Mr Putin and Mr Lavrov.
Referring to Mr Putin's wish to recover territory which previously fell under the USSR, Mr Johnson said Russia was "engaging in a revanchist mission to overturn the post-Cold War order".
Mr Johnson told allies "the UK would introduce sanctions against President Putin and foreign minister Sergei Lavrov imminently, on top of the sanctions package the UK announced yesterday", according to a No 10 spokesman.
"He warned the group that the Russian president's ambitions might not stop there and that this was a Euro-Atlantic crisis with global consequences," he said.
The Prime Minister also used the meeting to urge "immediate action" over the banning of Russia from the Swift payment system to "inflict maximum pain" on the Kremlin.
In a further move, Transport Secretary Grant Shapps announced he is extending a ban on Aeroflot flights landing in the UK to cover Russian private jets.
The move to sanction President Putin and Mr Lavrov comes after the European Union announced it was considering a similar move against the two men as it set out its latest round of measures in concert with the US and the UK.
The Government has faced criticism that it has still not gone far enough despite measures to hit five further oligarchs, and targeting more than 100 businesses and individuals.
With Russian forces continuing to advance towards Kyiv, beleaguered Ukrainian President Volodymyr Zelensky said sanctions had so far done nothing to deter the Russian onslaught.
Meanwhile Western officials have warned that the Russians could resort to thermobaric weapons - used to generate powerful, high-temperature explosions - if the Ukrainian military resistance continues to hold up their assault.
Despite beginning the attack on Thursday, the Russian forces have yet to take any of the main population centres and officials believe they failed to achieve most of their day one objectives for the invasion.
One official noted that the Russians were known to have thermobaric weapons in their armoury and that they had used them in previous conflicts.
"My fear would be that if they don't meet their timescale and objectives, they would be indiscriminate in their use of violence," the official said.
Britain's Chief of Defence Intelligence, Lieutenant General Sir Jim Hockenhull, said Russian forces were continuing to move towards Kyiv on two lines of advance.
"Their objective is to encircle the capital, to secure control of the population and change the regime," he said. "Ukrainian armed forces continue to offer strong resistance."
While there have been reports of sporadic fighting in the northern suburbs, most of the main Russian units were still thought to be more than 50km away.
President Putin stepped up his inflammatory rhetoric, urging Ukrainian troops to lay down their arms saying he would find it easier to negotiate with them, than "that gang of drug addicts and neo-Nazis who have holed up in Kyiv and have taken the entire Ukrainian people hostage".
Following the Nato meeting, alliance secretary general Jens Stoltenberg said it was clear the Kremlin's objectives were "not limited to Ukraine".
"We are facing a new normal in European security where Russia openly contests the European security order and uses force to pursue its objectives," he said.
He said the alliance was deploying thousands more troops to the eastern member states - who fear they could be the next target of Russian aggression - would "do what it takes to protect and defend every ally and every inch of Nato territory".
Earlier Defence Secretary Ben Wallace ruled out calls for Britain to help mount a no-fly zone over Ukraine because the RAF fighting Russian jets would trigger a "war across Europe".
