German authorities on Wednesday detained 25 members and supporters of a far-right group that the prosecutor's office said were preparing a violent overthrow of the state, with some members suspected of plotting an armed attack on the parliament.

One active soldier and several reservists are among those being investigated, a spokesperson for the military intelligence service said. The active soldier is a member of the Special Forces Command, it said.

A former parliamentary lawmaker from the far-right Alternative For Germany (AfD) who serves as a judge in Berlin was also among those detained, along with a former member of a German royal family. Investigators suspect individual members of the group had concrete plans to storm the Bundestag lower house of parliament in Berlin with a small armed group, the prosecutor's office said.