The northwestern German state formally banned the Concrete City charter and its supporter club Clan 81 and launched a crackdown against the groups on Wednesday.

Some 700 police officers were involved in the crackdown in over a dozen German cities, including Cologne, Wuppertal and Düsseldorf in North Rhine-Westphalia (NRW). Special police units, experts on organized crime and people acquainted with the "biker scene" also took part in the effort.

Read more: Hells Angels member charged in Frankfurt shooting

NRW state Interior Minister Herbert Reul said that both "the purpose and the activity of the biker club and its supporters goes against the law."

"The members of the club are proven criminals. Their everyday life consists of violence, weapons, drugs and forced prostitution," Reul said in a statement.

Hells Angels were attempting to lay claim to "power and territory" in their turf wars with rival clubs, he added.

"The state will not tolerate the growth of these parallel societies that disregard its authority and its monopoly on legitimate use of force," according to the minister.

Bikers to oppose the ban

The authorities have so far seized weapons, drugs, computers, and over 60,000 euro ($70,000) in cash belonging to the two groups, as well as bikers' "cuts" — the vests bearing symbols of their association.

The police crackdown is expected to continue until Wednesday afternoon. The coordinated action has been unfolding "without any incident," a police spokesman said.

Commenting on the raids, Hells Angels' lawyer Wolf Bonn accused the police of taking items which could not be considered evidence, including biker's watches, motorcycles, and even a bachelor thesis.

"We are now trying to form a comprehensive picture of the measures and people affected, and we are looking into legal moves to oppose the ban," the lawyer said.

Ensuring 'law and order'

Violent clashes between biker factions and biker-related crimes are relatively common in Germany, which has over 70 Hells Angels charters. In NRW, members of the world's best-known motorcycle club have a history of bloody rivalry with the Bandidos, also an international biker association

Read more: Cologne police raid Hells Angels hideout

Read more: Hamburg police arrests suspects in possible biker clash

A leader of a Hells Angels faction, Aygün Mucuk, was gunned down in the clubhouse in Wettenberg a year ago.

Earlier this year, around 40 Hells Angels members attempted to break through a police checkpoint in Cologne, allegedly to disrupt the birthday party for the local Bandidos leader. The police later raided the clubhouse, finding a firearm, a case of ammunition and a machete.

Last month, four Hells Angels bikers went on trial in Leipzig over a 2016 murder of a biker from a rival gang.

The Wednesday ban is part of a state-wide strategy of zero tolerance for biker gangs in NRW.

"We are going to make sure that there are law and order in the entire North Rhine-Westphalia," Interior Minister Reul said.

"This has nothing to do with this romanticized image of motorcycle riders. We are dealing with criminal organizations."

dj/msh (AFP, dpa)