Forensic doctors carrying out post-mortem on bodies in mass graves north of Kyiv said they have found evidence that some women were raped before being killed by Russian forces, The Guardian reported.

"We already have a few cases which suggest that these women had been raped before being shot to death," said Vladyslav Pirovskyi, a Ukrainian forensic doctor who with a team of coroners has carried out dozens of autopsies on residents from Bucha, Irpin and Borodianka who died during Russia's month-long occupation of the area.

"We can't give more details as my colleagues are still collecting the data and we still have hundreds of bodies to examine," he said, The Guardian reported.

Pirovskyi's team has been examining about 15 bodies a day, many of them mutilated.

"There are many burnt bodies, and heavily disfigured bodies that are just impossible to identify," he said, adding: "The face could be smashed into pieces, you can't put it back together, sometimes there's no head at all."

He said the bodies of some women they had examined showed signs that the victims had been killed by automatic gunfire, with upwards of six bullet holes in their backs.

Oleh Tkalenko, a senior prosecutor for the Kiev region, said details of alleged rapes had been forwarded to his office, which is investigating circumstances such as locations and the ages of victims, The Guardian reported.

"Rape cases are a very delicate and sensitive matter. Forensic doctors have a specific task of checking the genitalia of female victims and looking for signs of rape," Tkalenko said.

A foreign coroner who asked to remain anonymous said some bodies "are in such bad shape that it is not easy to find signs of rape or sexual abuse. But we are collecting evidence in a few cases of women we believe had been raped before being murdered".