A 21-year-old man from the German city of Hildesheim is facing investigation after threatening to kill Muslims on an internet forum, federal prosecutors said on Monday.
The suspect was apparently inspired by the Christchurch mosque attacker and made reference to the March 2019 shootings in New Zealand, in which 51 people were killed, prosecutors in the northern city of Celle said.
Weapons were found during a raid at his flat, as well as files containing right-wing extremist content, they added.
According to a statement, the online threat was made on May 29.
However, the man is thought to have been considering a mass-casualty assault for some time, with the goal of generating worldwide media attention.
He was taken into police custody the following day after a court arrest warrant was issued on charges of disturbing the peace by threatening to commit crimes, acquiring weapons and terrorist financing.
A police unit for investigating terrorist crimes has taken over the probe.