A former United Nations prosecutor has called for the International Criminal Court (ICC) to issue an arrest warrant for Russian President Vladimir Putin.
Carla Del Ponte, who was the chief prosecutor of UN war crimes tribunals for Rwanda and the former Yugoslavia, said the arrest warrant would restrict Putin from leaving Russia and "it would be a strong signal that he has many states against him".
"Putin is a war criminal," she told the Swiss newspaper Le Temps.
She said there are clear war crimes being committed in Ukraine, and added she was quite shocked by the use of mass graves.
"I hoped never to see mass graves again," Del Ponte told the newspaper Blick.
"These dead people have loved ones who don't even know what's become of them. That is unacceptable."
Other war crimes she found in Ukraine included attacks on civilians, destruction of civilian buildings, and the demolishing of entire villages.
She said an investigation into Ukraine would be easier than that in Yugoslavia because the country itself has requested an international probe. Current ICC chief prosecutor Karim Khan visited Ukraine last month.
If the ICC finds proof of war crimes, Del Ponte said "you must go up the chain of command until you reach those who took the decisions".
It could even be possible to bring Putin to account.
"You mustn't let go, continue to investigate. When the investigation into Slobodan Milosevic began, he was still president of Serbia. Who would have thought then that he would one day be judged? Nobody," she told Blick.
Del Ponte added that investigations should be made into war crimes carried out by both sides, pointing out that there's been alleged torture of Russian prisoners by Ukrainian forces.
It comes as Ukrainian President Volodymyr Zelensky accuses Russian soldiers of deliberately leaving mines in northern Ukraine as they withdraw or are pushed out by Ukrainian forces.
Ukraine says its troops have regained control of more than 30 towns and villages in the Kyiv region since Russia announced this week it would scale down its operations around the capital and in the neighbouring northern region of Chernihiv to focus on battles in the east.
"In the north of our country, the invaders are leaving. It is slow but noticeable. In some places they are being kicked out with fighting. Elsewhere they're abandoning the positions themselves," Zelensky said on Saturday.
"They are mining all this territory. Houses are mined, equipment is mined, even the bodies of dead people."
Chernihiv Governor Viacheslav Chaus also accused Russian troops of leaving mines as they withdrew from their positions around Kyiv.
"There are a lot of mines. They [the villages] are strewn with them," he said on Saturday.
Zelensky said they are trying to clear mines and secure the areas, but told residents who had fled to stay away for now.
