German lawmakers are calling for a review of security arrangements at the Bundestag lower house of parliament after authorities detained members of a far-right group that they say were preparing a violent overthrow of the state.

German authorities on Thursday ordered 23 people to be held for questioning as they investigate the group. A former lawmaker from the far-right Alternative For Germany (AfD) was among those detained, according to German prosecutors.

Greens lawmaker Konstantin von Notz, chairman of the parliamentary committee that oversees the intelligence services, said the Bundestag’s security arrangements were not made for “enemies of the constitution” to be elected to parliament.

“We have to increase the protection concept for the Bundestag without sabotaging the everyday life of democratic lawmaker,” he told Redaktionsnetzwerk Deutschland.

The AfD has condemned the far-right group’s efforts and expressed confidence in the authorities’ ability to bring clarity to the situation quickly and completely.

Social Democrat lawmaker Sebastian Hartmann told the Funke media group: “The Bundestag should also review its security concept. Personally, I feel safe, but my confidence is not boundless.”

Investigators have said the group, many of whom were members of the movement Reichsbuerger (Citizens of the Reich), planned to install aristocrat Heinrich XIII Prinz Reuss as leader of a new state and found evidence that some members planned to storm the German parliament and seize lawmakers.

Members of the Reichsbuerger do not recognise modern-day Germany as a legitimate state. Some of them are devoted to the German empire under monarchy, while some are adherents of Nazi ideas and others believe Germany is under military occupation.

“For the Bundestag, we will carefully examine which security measures we need to adapt,” Katrin Goering-Eckardt, vice president of the Bundestag, told the Funke media group.

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