German President Frank-Walter Steinmeier is calling for a war crimes tribunal against Russian President Vladimir Putin and Foreign Minister Sergei Lavrov, according to German magazine Der Spiegel.

"Anyone who has responsibility for these crimes will have to explain themselves," Steinmeier told Der Spiegel in an interview.

"That includes soldiers. That includes military commanders. And of course, those who have political responsibility," he said.

Germany's intelligence agency intercepted radio messages from Russian military sources discussing the killing of civilians in the Ukrainian town of Bucha, Der Spiegel reported on Thursday.

It said the agency presented the findings in parliament on Wednesday without giving a source for the information.

Russian troops occupied Bucha, 37 kilometers (23 miles) northwest of Kyiv, for more than a month following their Feb. 24 invasion of Ukraine. Local officials say Russian forces killed more than 300 people in Bucha alone, and around 50 of them were executed.

Ukraine has accused Russia of genocide and war crimes. On Tuesday, the Kremlin said Western allegations that Russian forces executed civilians in the Ukrainian town of Bucha were a "monstrous forgery" meant to discredit the Russian army and justify new Western sanctions.