A top Cabinet Minister has raised fears Russia is committing genocide in Ukraine and warned the world must act to stop "mass murder on an unprecedented scale".
Health Secretary Sajid Javid expressed horror at the atrocities uncovered as Russian forces withdrew from towns around Kyiv and compared the scenes to the Srebrenica massacre in Bosnia in 1995.
Ukrainian troops have been showing journalists grim scenes of bodies of civilians, destroyed houses and burnt-out cars in the streets in Bucha.
"This is mass murder on an unprecedented scale in Europe. We haven't seen the likes of this I think since 1995," he told BBC Breakfast.
"I don't want to be commemorating another genocide in Europe years from now.
"We have the power, the world has the power to stop this, and it must act."
Ukraine has compared the mass graves found outside Bucha, north-west of Kyiv, to the Srebrenica massacre in July 1995 when Bosnian Serb forces killed men and boys in what is regarded as Europe's worst atrocity since the Second World War.
The UK Government has said it appears Putin's forces are committing war crimes but it has not gone as far as declaring the Russians have enacted genocide in Ukraine
Former British Army chief Lord Dannatt said Russia's war in Ukraine increasingly looks "like genocide that is plotted from the top".
He told Sky News: "The war crimes are stacking up to the point that it looks like a concerted effort to reduce the Ukrainian population, and that is getting very close to the definition of genocide.
"It's absolutely right and proper that all these war crimes are being chronicled and evidence is being gathered.
"It is looking to me increasingly like genocide that is plotted from the top. The top, therefore, must bear responsibility and maybe one day, even if not in a physical court but in a court of history, be condemned."
Lord Dannatt was unsure if Vladimir Putin or his senior generals would face trial, but added that it is still possible.
He told the programme: "If you think back to the early, dark days of the Bosnian civil war, it seemed inconceivable that Milosevic (former Serbian leader Slobodan Milosevic) and Karadzic (Bosnian Serb former leader Radovan Karadzic) would find their way into court, but they did.
"It became perfectly possible to trace what had happened on the ground all the way up to them through this concept of command responsibility such that they were convicted."
It comes as the West was poised to impose further sanctions on Russia, as NATO foreign ministers hold emergency talks in Brussels today.
Alliance envoys, including Foreign Secretary Liz Truss, US Secretary of State Anthony Blinken and coalition Secretary-General Jens Stoltenberg, meet for negotiations at its Brussels headquarters as fighting continues in Ukraine.
Ms Truss is set to use the two-day NATO summit to press for tougher sanctions against Russia. US officials said they expected to see coordinated measures by Western allies, including a ban on all new investment in the country.
Other moves could include new restrictions on financial institutions and state-owned enterprises, and sanctions on government officials and their family members.
