GENEVA (AFP) - The United Nations said Tuesday (April 5) that all the signs from Bucha pointed towards civilians having been directly targeted and killed in the town outside Kyiv.

The UN Human Rights Office said the images emerging from the Bucha were extremely disturbing, and underlined that international law prohibited deliberate attacks on civilians.

Western leaders have united in outrage after dozens of bodies were found on the streets and in mass graves when Russian troops retreated from the devastated town, laying bare the horrors of a 40-day war that has killed thousands.

"What we're talking about here appears to be the direct killing and targeting of civilians in Bucha," rights office spokeswoman Liz Throssell told reporters in Geneva.

She cited photographs of people with their hands bound and of partially naked women whose bodies had been burnt.

"This is extremely disturbing, and does really strongly suggest that they were directly targeted as individuals, and here, what we must stress is that under international humanitarian law, the deliberate killing of civilians is a war crime," she said.

Ms Throssell added: "All the signs are that the victims were directly targeted and directly killed.

"You could argue there was a military context, for example, to a building being hit; it's hard to see what was the military context of an individual lying in the street with a bullet to the head or having their bodies burned."

Ms Throssell clarified that the Office of the United Nations High Commissioner for Human Rights did not have staff on the ground in Bucha.

Ukrainian President Volodymyr Zelensky blames Russian troops for the killings, but the Kremlin has denied responsibility. Moscow suggested images of the corpses in Bucha were "fakes".