The mother of a Russian student who gave an anti-war speech in the German parliament says he has received intimidating threats, even as the Kremlin has urged for calm.

In a visit to the Bundestag, Nikolai Desyatnichenko, a teenager from the northern industrial city of Novy Urengoy, described the story of a 21-year-old German soldier taken captive after the battle of Stalingrad who died “in the severe conditions of captivity.”

Desyatnichenko said he had been moved by a visit to the grave of Wehrmacht soldiers in the Chelyabinsk region.

"Innocent people were killed there, many of whom wanted to live in peace and did not wish to fight,” he said.

Footage of the speech was uploaded to YouTube and his school’s page on social network VK. The video has since become inaccessible.

The speech triggered an uproar among conservatives in the Russian parliament and state media, which generally glorify Soviet forces in World War II.

“He's being insulted and called names, and being threatened that they're going to get him," state news agency TASS quoted Nikolai’s mother as saying.