These "deeply disturbing" reports point to support for Russia from Chinese state actors, in particular the Chinese People's Liberation Army, it said.

The envoy was summoned on Thursday, it added.

"Anything that enables Russia to continue its war of aggression against Ukraine also represents a threat to our security," the ministry said.

The German government regularly stresses its concern over China's support for Russia.

This was notably the case during Chancellor Friedrich Merz's visit to China in February, the ministry said, adding that it is "addressing this issue in depth with its European partners."

On May 20, the German daily Die Welt reported that the Chinese army had secretly trained several hundred Russian soldiers on its territory, some of whom had been deployed in Ukraine, citing classified documents from European intelligence services.

These revelations, which could not be independently verified by AFP, emerged in the middle of a summit in Beijing bringing together the leaders of the two allies, Vladimir Putin and Xi Jinping.