A top E.U. official proposes a special court for alleged Russian crimes.

Kyiv has redoubled its push to persuade world leaders to create an international tribunal to hold Russian soldiers and top Moscow officials accountable for atrocities in Ukraine.

On Wednesday, Ursula von der Leyen, the president of the European Commission, the European Union’s executive arm, proposed the establishment of a specialized, United Nations-backed court “to investigate and prosecute Russia’s crime of aggression.” Although there would be several procedural hurdles to overcome before such a court could be set up, the call reflected support among top Western leaders for accountability for atrocities.

“We are ready to start working with the international community to get the broadest international support possible for this specialized court,” Ms. von der Leyen said in a statement.

The new court would be a further demonstration of how seriously Europe, the United States and the United Nations take accusations of Russian crimes since Moscow launched its full-scale invasion of Ukraine in February. Ukraine has already staged several of its own war-crimes trials, and a plethora of international bodies are investigating accusations of atrocities. But establishing the burden of proof for the most serious crimes is notoriously difficult.

President Volodymyr Zelensky made a plea for an international tribunal in his nightly address on Tuesday, the same day that justice ministers from the Group of 7 nations discussed a proposal to create a war-crimes tribunal in Berlin and Ukraine’s first lady made the case to British lawmakers.

Investigators have documented evidence of possible Russian war crimes since the war’s early days, including the execution of civilians in Bucha, a Kyiv suburb, in March.

More recently, retreating Russian forces have left behind unmarked mass graves and torture rooms. After it was recaptured by Ukrainian troops in September, a mass burial site was found near the town of Izium, with many of the dead showing signs of torture. Civilians killed execution-style were also found this month in the southern Kherson region.

The Kremlin rarely comments on accusations against its forces. It has denied that its troops attack civilians.

Russian and Ukrainian soldiers have both been accused of war crimes, although the number and scale of reported Russian crimes are far greater.

Videos that surfaced on social media this month have raised questions over whether Ukrainian forces committed war crimes when they captured and killed a group of Russian soldiers in the Luhansk region. While Russia accused Ukraine of needlessly killing Russian prisoners of war, Ukraine’s commissioner for human rights, Dmytro Lubinets, said Russian soldiers had opened fire during the act of surrendering.

For months, Mr. Zelensky has called for a special tribunal to examine wartime atrocities and work alongside the International Criminal Court. His administration is working to drum up global support to get behind a draft resolution to present to the United Nations General Assembly.

“We must develop the necessary legal architecture to make the tribunal work,” he said in his nightly address on Tuesday, referring to the Nuremberg tribunal established in Germany to hold Nazis accountable after World War II.

Mr. Zelensky maintained that there was no judicial body to charge all Russian officials. Even at the level of the International Criminal Court, he said, “it is still impossible to bring the highest political and military leadership of Russia to justice for the crime of aggression against our state.”

Hie wife, Olena Zelenska, called for accountability in an address to Britain’s lawmakers in Westminster on Tuesday. “Victory is not the only thing we need,” she said. “We need justice.”

The same day, Ukraine’s prosecutor general, Andriy Kostin, pressed for the international tribunal in a meeting with the ministers of the Group of 7 countries in Berlin.

“Prosecutors perform their duties even under enemy fire, but we need help to continue this work,” he said on Tuesday, according to a statement from the prosecutor general’s office on the Telegram social media app.

Emma Bubola contributed reporting.