The European Union wants to work with the International Criminal Court to create a United Nations-backed tribunal to investigate war crimes in Ukraine that could lead to an indictment of Russian President Vladimir Putin.

"Russia must pay for its horrific crimes," EU Commission President Ursula von der Leyen tweeted Wednesday. "We will work with the ICC and help set up a specialized court to try Russia's crimes."

In September, Ukraine's prosecutor general, Andriy Kostin, said his office documented 34,000 potential war crimes committed by Russian forces since Putin ordered the invasion in February, and is mounting a case for genocide, the BBC reported.

Mass burial sites have been found in areas once occupied by Russian forces. In April, 400 bodies of civilians were found in Bucha on the outskirts of Kyiv, and in September, 450 bodies, mostly civilian, were found in mass graves in Izium in the Kharkiv region.

A Russian airstrike March 16 hit the Mariupol Drama Theater, which was used as a refuge for children, resulting in 600 deaths, according to the Associated Press. Also in March, a Russian airstrike hit a maternity and children's hospital in Mariupol, killing three, including a child, and injuring 17.

"Russia's invasion of Ukraine has brought death, devastation and unspeakable suffering," von der Leyen said in a video attached to her tweet. "We all remember the horrors of Bucha."

The EU wrote in a news release that investigations of Russian war crimes are underway in 14 member states and the ICC. But because Russia does not recognize the ICC's jurisdiction, the crime of aggression, committed by the highest political and military leadership, cannot be prosecuted by the ICC.

The EU said it leaves two options available, both needing backing by the U.N.: A special independent international tribunal based on a multilateral treaty or a specialized court integrated in a national justice system with international judges.

Von der Leyen also called in the video for Russia to front the costs of rebuilding Ukraine once the war ends. She said the war has cost damage totaling 600 billion euros ($626 billion).

"And we have the means to make Russia pay," she said. "We have blocked 300 billion euros ($313 billion) of the Russian Central Bank reserves. And we have frozen 19 billion euros ($19.8 billion) of Russian oligarchs' money. In the short term, we could create with our partners a structure to manage these funds and invest them. We would then use the proceeds for Ukraine."

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