Around 600 delegates from the AfD had gathered at the two-day congress in the northern German city on Saturday to elect a new leadership duo from its nationalist wing after the party garnered nearly 13 percent of the votes and almost 100 seats in parliament in general elections in September.

The party’s incumbent leader, Joerg Meuthen, was re-elected as chairman, and Alexander Gauland was elected as co-chair of the far-right party.

Before and during the congress meeting, anti-AfD demonstrators staged a mass rally in Hanover and held banners and placards that read “Hanover against Nazis,” and “Stand up to racism.”

Scuffles broke out as dozens of protesters and leftist activists blocked a road leading to the congress, prompting riot police already deployed to use water cannons to disperse the crowd and remove some of the blockades.

Several officers sustained injuries in clashes, and a demonstrator who had chained himself to a barricade suffered a broken leg and was taken to hospital, according to police sources.

The AfD became the country’s third-biggest party in general elections on September 24 and is now represented in 14 of Germany’s 16 state parliaments; but it has been shunned by mainstream parties as a potential partner at the national level.