Speaking over videos of dead Ukrainians lying in the streets, Mr Johnson said: “Civilians massacred – shot dead with their hands tied.

“Women raped in front of their young children.

“Bodies crudely burned, dumped in mass graves, or just left lying in the street.

“The reports are so shocking, so sickening, that it’s no wonder your government is seeking to hide them from you.

“Your president knows that if you could see what was happening, you would not support his war,” he said.

“He knows that these crimes betray the trust of every Russian mother who proudly waves goodbye to her son as he heads off to join the military.

“And he knows they are a stain on the honour of Russia itself.”