Ukrainian MPs have accused Russian forces of raping women over 60 years old before hanging them.
Lesia Vasylenko, an MP for Ukraine ’s opposition Holos party, said many female “senior citizens” had committed suicide after they were sexually abused, in a bid to escape the violence.
Others were so vulnerable they could not escape, she claimed.
Speaking to journalists in the House of Commons, Ms Vasylenko said Vladimir Putin has "changed his strategy to target the most vulnerable groups of women and children".
“Most of [the women over 60] were executed after being raped or took their own lives.
"The main problem is that victims and families do not have the strength or capacity to come forward," Ms Vasylenko said.
Maria Mezentseva, Ukrainian MP for Servant of the People Party added: "The ladies who were raped and suffered sexual violence, some of them were also hanged.
"These are the facts we are gathering for evidence on war crimes and to take to the ECHR."
She called on the Government to provide targeted humanitarian support within Ukraine so victims can get “proper assistance”.
It would also enable the crimes to be "properly documented" so they have more evidence against Putin so he can be tried for war crimes at the international criminal court in The Hague.
The vulnerable groups of women are said to have been targeted around around the vicinities of Kyiv, in Bucha and Irpin.
Ms Vasylenko said: "It's a tragedy that no one has found ways to help the victims.
"They do not have the strength or the capacity to come forward".
Ms Vasylenko and Ms Mezentseva spoke alongside two other MPs; Alona Shkrum from Ukraine's Batkivschyna party and Olena Khomenk who left Kyiv to meet Boris Johnson alongside the likes of Home Secretary Priti Patel, Foreign Office Minister James Cleverly, Communities Secretary Michael Gove Defence Minister James Heappey.
The MPs, in the Commons, echoed Ukraine President Volodymyr Zelensky's comments that there was no point in living if you couldn't stop innocent lives being lost.
Addressing US Congress on Wednesday, Mr Zelensky told US politicians: "Now I'm almost 45 years old.
"Today my age, stopped when the heart of more than 100 children stopped beating. I see no sense in life, that cannot stop the deaths."
The Ukrainian MPs in the Commons added: "We feel very much the same."
Describing the terror Putin's forces had created amongst the most vulnerable, Ms Shkrum added: “Right now children have been deliberately shot because Putin has given the order to create as much human terror as possible."
"Russians have created this new Hitler and they need to start stopping him also. They need to start listening they need to start asking questions where the soldiers are going to."
The humanitarian crisis in Ukraine has deepened as Russian forces are resorting to "medieval tactics" they claimed, blasting routes humanitarian convoys could have used to bring essentials like food and water into Mariupol.
Heat, food, water and medicine has become increasingly scarce in the region as aid agencies are struggling to operate.
Last week, Ukraine’s foreign minister Dmytro Kuleba accused Putin’s troops of committing sex attack as they invaded cities.
He said there were “numerous” cases of women being targeted.
Speaking to the Chatham House foreign affairs think-tank via a video link, he said: "When bombs fall on your cities, when soldiers rape women in the occupied cities - and we have numerous cases of, unfortunately, when Russian soldiers rape women in Ukrainian cities - it's difficult of course to speak about the efficiency of international law.
“But this is the only tool of civilisation that is available to us, to make sure that in the end, eventually, all those who made this war possible will be brought to justice, and the Russian Federation, as a country that committed an act of aggression, will be held accountable for its deeds.”
