At a summer party of the SPD parliamentary group, several women were probably the victims of an attack with so-called knockout drops.
"This is an outrageous event, which we immediately reported to the Bundestag police," says a letter from SPD parliamentary group leader Mathias Martin to the members of the Bundestag and their employees, from which the "Tagesspiegel" quoted on Friday and also the German press agency was available.
"We recommend that other people affected report this to the police immediately," it said.
The parliamentary group's first secretary, Katja Mast, said: "We are all appalled and will do everything in our power to clarify this incredible process." She also advised those affected to report it.
The parliamentary group leadership can be contacted at any time by those affected.
Internal party chat: eight affected, one case confirmed by test
The "Tagesspiegel" also quoted from an internal party chat in which eight people affected were mentioned.
A case was confirmed by a test and a complaint was made against unknown persons.
The summer party took place on Wednesday at the Chancellery in Berlin. In addition to SPD MPs and employees in the Bundestag and the constituencies, Chancellor Olaf Scholz also took part.
According to the "Tagesspiegel", there were around 1000 guests at the farm festival - significantly fewer than usual in the past due to the corona pandemic.