Washington, Apr 5 (IANS): US President Joe Biden has called for a "wartime trial" against Russia over the alleged civilian killings in the Ukrainian city of Bucha, where a mass grave has been found with more than 300 bodies.

Addressing the media on Monday, Biden said: "I got criticised for calling (Russian President Vladimir) Putin a war criminal. Well, the truth of the matter — you saw what happened in Bucha. This warrants him — he is a war criminal.

"But we have to gather the information, we have to continue to provide Ukraine with the weapons they need to continue the fight, and we have to get all the detail so this can be an actual — have a wartime trial."

The American President went on to call Putin "brutal", adding that the incident in Bucha was "outrageous".

When asked if he agreed the alleged Bucha killings was a genocide, Biden said: "No, I think it is a war crime."

The President added that he was seeking more sanctions against Putin, but did not provide any further details.

The city of Bucha, along with Monastyrskyi, Irpin, Hostomel, Borodyanka, Makariv, Kopyliv, Motyzhyn, all in the Kiev region, were liberated from Russian forces on April 2.

Later that day, Bucha Mayor Anatoliy Fedoruk announced that a mass grave was discovered in the city where almost 300 people were buried.

Ukraine's Prosecutor General Iryna Venediktova said there was "crucial evidence of brutal war crimes perpetrated by the Russian Federation in the liberated territories of the Kiev region".

Russia has however denied the allegation, saying that the photos and videos published of the carnage in Bucha had been faked by the Kiev government.

The developments in Bucha have received widespread condemnation.

While Ukrainian President Volodymyr Zelensky has termed the killings as "genocide", UK Prime Minister Boris Johnson accused Russia of "despicable attacks" and US Secretary of State Antony Blinken called it a "punch to the gut".

Head of the European Commission, Ursula von der Leyen, said an independent investigation was urgently needed.

German Chancellor Olaf Scholz condemned it as a "terrible war crime" and French President Emmanuel Macron called pictures from the scene "unbearable".