The experts, who are mandated by the Human Rights Council but do not speak on behalf of the UN, said they had sent Russia a dossier detailing 10 cases of Ukrainian civilians tortured while under Russian occupation.

All were administered “repeated electric shocks, including to the genitals” by the Russians, who also beat, kicked, blindfolded and acted out mock drownings and executions on their captives, the experts’ statement said.

“These separate allegations, capturing the experiences of four women and six men, are truly grisly,” said Alice Jill Edwards, the UN’s Special Rapporteur on Torture, warning that they were “only a small snapshot of a wider, well-documented pattern”.

“These were all highly-sexualised assaults which included rapes, threats of rape, and other depraved conduct,” Edwards said.

“It is becoming clearer that the Russian Federation’s deliberate and systematic policy of torture in Ukraine involves sexualised torture and other sexualised cruelty, including against the civilian population,” the rapporteur added.

“The Russian Federation is using torture to intimidate, instil fear and control civilians in occupied territories of Ukraine.”

The experts urged the Russian government to explain both the specific allegations detailed in the dossier and what it was doing to prevent sexual torture within the ranks.

One of the female victims remains detained inside Russia, the experts added, calling for her immediate release.