Speaking to the top-selling Bild newspaper, Wong said: "It makes me furious that the German Bundeswehr is apparently helping to train Chinese soldiers. Given the riots in Hong Kong, the defence ministry should have ended this programme long ago."

The sudden emergence of soldiers from the Chinese People's Liberation Army on the streets of Hong Kong Saturday rattled nerves in the semi-autonomous territory, rocked by months of increasingly violent anti-government protests.

In a rare and highly symbolic troop movement, the plainclothes soldiers briefly left their Kowloon barracks to help clean up debris and bricks from the protests.

Wong also told Bild that Hong Kong security forces were using "German water cannon" against protesters.

"When will their export be stopped?" he asked.

Amnesty International backed Wong's plea to end the military training.

"Given the current situation in Hong Kong, the German government should send a clear signal and immediately end any military cooperation," Mathias John, an expert in arms and human rights at Amnesty International in Germany, told Bild.

According to the daily, the German military plans to give 11 PLA soldiers logistics and senior officer training in 2020.

Wong, 23, has visited several countries in recent months to drum up foreign support for Hong Kong's activists.

He met with German Foreign Minister Heiko Maas in September, prompting Beijing to summon Germany's ambassador in anger.

In a separate interview to appear in Monday's edition of the German Sueddeutsche daily, Wong justified the use of violence against police by Hong Kong's anti-government demonstrators.

"We won't achieve our goals through purely peaceful protest alone," he said, in comments translated into German.

"Nor through violence alone. We need both," he added.