Open this photo in gallery A counter demonstrator holds a sign reading 'Berlin against Nazis' as he and others make their way to block a Neo-Nazis gathering intended to commemorate the anniversary of the death of Rudolf Hess on August 18, 2018 in Berlin, Germany. Hess was a leading member of the Nazi party under Adolf Hitler. He attempted in a solo mission to negotiate peace with the Allies in 1941, was later sentenced to life in prison and committed suicide in 1987. Omer Messinger/Getty Images

At least one police officer was injured in Berlin on Saturday when around 500 activists shouting “Nazis out” clashed with an equal number of far-right activists marking the 31st anniversary of the prison suicide of Nazi convict Rudolf Hess.

Many of the far-right activists, clad in red and white, hoisted the red, white and black flag of Hitler’s Third Reich. One group carried a sign that proclaimed, “I regret nothing: National Socialists Berlin.

“There were reports of injuries when some stones and bottles were thrown by counter demonstrators at the far-right demonstrators,” Berlin police spokesman Thilo Cablitz told Reuters. “At least one police officer was injured. But the event is still going on and we’re still compiling the numbers.”

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About 2,300 police officers were on duty to prevent violence at the Berlin event and a separate march by less than 50 people in the Berlin suburb of Spandau, where Hess, a former deputy of Germany’s wartime dictator Adolf Hitler, served a life sentence handed down at the Nuremberg war crimes trials.

A broad mix of counter demonstrators staged non-violent sit-ins at intersections along the march route in the Berlin neighbourhood of Lichtenberg, while others gathered to shout at the neo-Nazi demonstrators.

Germany has tough laws that ban use of symbols of the Nazi regime, such as the swastika flag, but the far-right has grown stronger in recent years after the arrival of more than a million mostly Muslim migrants beginning in 2015.

While far-right activity remains a fringe phenomenon in Germany, it has been behind high-profile crimes, most recently 10 murders committed by the so-called National Socialist Underground (NSU), whose sole surviving leader was sentenced to life in prison in July.

The clashes took place about 65 km (40 miles) south of the town of Meseberg, where Chancellor Angela Merkel is meeting Russian President Vladimir Putin on Saturday evening.