The German Federal Office for Migration and Refugees said it had received a tip last year about the man accused of the attack on the Magdeburg Christmas market that killed five people, DPA reported.
The tip came via social media at the end of 2023, the office wrote in "Ex".
"This, among many other indications, was taken seriously," they said.
Since the immigration office is not an investigative body, information about the tip and its sender was forwarded to the competent authorities, the publication said.
Screenshots are circulating on the Internet showing messages in which a specific person warns the office about the alleged perpetrator, Taleb A.
The reliability of these screenshots cannot be independently verified.
Taleb A., whose full identity is not being released due to German privacy laws, was charged earlier today with premeditated murder, attempted premeditated murder and other crimes.
Five people were killed and 200 were injured in the attack on Friday night.