Ukraine's Foreign Minister today claimed the "horrors" of Bucha are just the "tip of the iceberg" as he accused Russia of "rape, torture and killings".
Dmytro Kuleba said besieged Mariupol is "even worse" than Bucha, near Kyiv, where images of charred bodies and mass graves emerged after Ukraine retook the area.
Standing alongside UK Foreign Secretary Liz Truss in Poland, he backed her call to expel Russia from the UN Human Rights Council and warned: "Half measures are not enough any more."
He invited all Western leaders still dithering over sanctions to visit Bucha and "stand in front of the mass grave. To see the bodies of dead Ukrainian women who had been raped before being killed and who the Russians tried to set on fire to hide the traces of their crimes.”
Bucha's deputy mayor said on Sunday that 50 residents had been victims of extra-judicial killings carried out by Russian troops.
The Kremlin on Monday denied any accusations related to the murder of civilians in Bucha.
"This information must be seriously questioned," Kremlin spokesperson Dmitry Peskov told reporters. "From what we have seen, our experts have identified signs of video falsification and other fakes."
But Mr Kuleba told journalists in Warsaw: “The horrors that we’ve seen in Bucha are just the tip of the iceberg of all the crimes that have been committed by Russian Army in the territory of Ukraine so far.
"And I can tell you without exaggeration and with great sorrow that the situation in Mariupol is much worse compared to what we’ve seen in Bucha and other cities, towns and villages nearby Kyiv.”
He said the "horrors" demand “serious G7 and EU sanctions”. He added: "The West continues to fill the Russian war machine with payments for Russian fossil fuels, with trade still taking place between Russia and western countries.
"Half measures are not enough any more."
Calling for tougher sanctions he added: "This is not the request of Ukraine’s Foreign Minister - this is the plea of the victims of rape, torture and killings, their relatives and the entire Ukrainian nation."
He invited people who still buy Russian gas, oil and coal - or who still doubt whether to block Russia from SWIFT or block Russian ships from their ports - to stand at a mass grave of raped women.
He said: “I invite all of them to visit Bucha without any delay.
“To visit a small village and stand in front of the mass grave.
“To see the bodies of dead Ukrainian women who had been raped before being killed and who the Russians tried to set on fire to hide the traces of their crimes.”
He added: “And I do this address to all foreign ministers who will be meeting this week at NATO, at the EU, at the G7 ministerial. If you have doubts, reluctance or arguments about the need to keep doing business with Russia, go to Bucha first, and then talk to me.”
It comes as leaders of western nations prepare to gather in Brussels from tomorrow to discuss the latest response.
UK Foreign Secretary Liz Truss said she would be pressing for a "tough new wave of sanctions" and said Russia had "no place on the human rights council" of the UN.
She said the UK will be going after Russian ships, banks, gold, and seeking a "clear timetable to limit our imports" of Russian oil, gas and coal. "Being tough is the only approach that will work. Putin has escalated this war," she said.
After US President Joe Biden branded Putin a war criminal she added: "We need justice done at the International Criminal Court."
She also called for further weapons to be supplied to Ukraine to combat Vladimir Putin's invasion.
Mr Kuleba said "Ukraine won the battle for Kyiv - but the war goes on".
