Twenty-five women and girls have said they were raped by Russian forces in Bucha, a senior Ukrainian official has told the BBC.
Lyudmyla Denisova, the Ukrainian Parliament's Human Rights Commissioner, said a telephone helpline offering support had received at least 25 reports of rape of women and girls aged between 14 and 24 by Russian soldiers.
She said Ukraine had evidence of "genocide of Ukrainian people" and of military crimes, adding that rape was "the new weapon" of Russian forces.
Denisova added: "Together there were 25 women aged 14-24 that were raped by Russian soldiers.
"That was happening for a month. We will keep documenting these terrible crimes, unfortunately, and every criminal will be punished."
Russia has denied carrying out atrocities in Bucha.