Russian soldiers have been accused of carrying out "genocide" amid evidence of mass graves, torture and bodies lying in the streets as Kremlin forces pull back from Kyiv.

President Volodymyr Zelenskyy called Russian soldiers "killers, executioners, rapists, marauders" while Moscow categorically denied killing civilians in Bucha.

British Foreign Secretary Liz Truss said that Russia must be suspended from the United Nations Human Rights Council over the discovery of bodies and mass graves found in the town.

Germany said it had expelled 40 Russian envoys over the atrocities in Bucha - adding that further measures with allies are being prepared.

Ukraine war latest - 'Unspeakable horrors' in liberated towns as satellite images show mass graves

Ukraine officials say some victims were shot in the head with their hands tied behind their back and there has been international outrage and allegations of war crimes levelled at the Kremlin.

Some western leaders have also called for further sanctions in response to the alleged atrocities - even as Putin's forces continued to press its offensive in the east.

Once a popular commuter town located around 16 miles outside the capital, Bucha was ravaged by heavy fighting before being liberated by Ukrainian forces over the weekend.

Key developments:

• Russian forces continue to "consolidate and reorganise" as they focus on the Donbas region in eastern Ukraine, according to the UK's Ministry of Defence
• Allegations of war crimes and genocide in town of Bucha amid evidence of mass graves
• Moscow categorically denies its forces have killed civilians in Bucha
• The European Union is preparing further sanctions and support
• UK Foreign Secretary Liz Truss will travel to Poland on Monday where she will push for tougher economic measures against "the Putin war machine".

There has been international outcry over the scenes of death and destruction revealed over the weekend as Ukrainian forces have pushed further outwards from Kyiv and liberated surrounding towns.

Images emerged on Sunday of Ukrainian civilians lying on the streets of Bucha, with witnesses saying the victims were killed by Russian forces without any apparent provocation - allegations Moscow has denied.

Bucha's mayor, Anatoliy Fedoruk, said more than 300 residents had been killed, while Ukrainian prosecutors said they have found 410 bodies in towns near the capital.

Some of the victims had their hands tied and were shot in the back of the head, Ukrainian authorities said.

One resident of Bucha said Russian troops went from building to building and took people out of the basements where they were hiding.

He said soldiers checked their phones for evidence of anti-Russian activity and took them away or shot them.

Zelenskyy calls Russian soldiers 'killers, executioners, rapists, marauders'

President Zelenskyy accused Moscow forces of carrying out "a genocide", saying that a "concentrated evil has visited our land".

He said: "The killers, executioners, rapists, marauders who call themselves an army - and who deserve only death after what they've done."

The Ukrainian leader has visited the freshly-liberated town as he continues to call for further global support.

Russia's Defence Ministry rejected the accusations of atrocities against civilians in Bucha and other suburbs of Kyiv.

Russian Foreign Minister Sergey Lavrov also rejected the allegations, describing the scenes outside Kyiv as a "stage-managed anti-Russian provocation."

Moscow will push for a meeting of the UN's Security Council to discuss what it called "Ukrainian provocations" in Bucha.

French President Emmanuel Macron said there is "clear evidence of war crimes" in Bucha.

He told France-Inter radio: "What just happened in Bucha calls for a new round of sanctions and very clear measures.

"I'm in favour of a new round of sanctions and in particular on coal and petrol. We need to act."

The UK's Liz Truss tweeted: "Given strong evidence of war crimes, including reports of mass graves and heinous butchery in Bucha, Russia cannot remain a member of the UN Human Rights Council. Russia must be suspended."

She added: "The UK, Poland and our allies are stepping up the pressure on Russia over its illegal invasion of Ukraine.

"I'm in Warsaw to talk to the Polish government, our steadfast partners in supporting Ukraine."

Meanwhile, European Council president Charles Michel tweeted that the EU is assisting Ukrainians and rights groups in gathering evidence to be used in international courts, adding that "further EU sanctions & support are on their way".

Spanish Prime Minister Pedro Sanchez also called for those responsible for the killings in Bucha to be held accountable, saying they should "answer these alleged cases of crimes against humanity, war crimes and, why not say it, of genocide, too".

Kremlin forces focusing on Donbas region, UK MoD says

Allegations of war crimes come as Russian forces are continuing to "consolidate and reorganise" their efforts as they refocus their offensive on the Donbas region in Ukraine's east, where they are being joined by Wagner mercenaries, according to the UK's Ministry of Defence.

By the coast, aid workers with the International Committee of the Red Cross (ICRC) were not able to reach Mariupol on Monday due to "security concerns" as the city continues besieged by Russian forces, the organisation said.

Meanwhile UK Foreign Secretary Liz Truss will visit Poland on Monday to call for tougher sanctions on Russia as Western countries work together to ramp up economic pressure on the Kremlin.

In a message on Twitter, Prime Minister Boris Johnson said: "All the tanks and guns in Vladimir Putin's arsenal will never break the spirit of Ukraine's people or conquer their homeland."

"Britain will never waver from supporting our friends", he added.

It comes as the UK leader seeks to galvanise a tougher response from Western allies, including NATO members, against Russia.

Meanwhile, the European Council's President Charles Michel said the European Union is preparing further sanctions following the actions of Russian forces in Bucha.