The 31-year-old Russian man was arrested in Berlin.
German authorities Wednesday detained a man at an apartment in Berlin suspected of planning a "serious state-damaging act of violence," according to Germany's Federal Prosecutor's Office.
Russian national Magomed-Ali C, 31, is thought to be the accomplice of French native Clement Baur, who was arrested on terror charges in Marseille, France, last year.
Magomed-Ali C is suspected of having "prepared a bomb attack" in 2016 with the Frenchman.
The 31-year-old's apartment in Berlin was searched in 2016 and found to contain "a considerable amount of TATP" — triacetone triperoxide, an explosive used in the attacks in Paris on November 13, 2015, and Brussels in March 2016 — said the German anti-terror prosecutor in a statement.
"The accused, a member of the radical Islamist movement, wanted to make an explosive with his accomplice, currently held in France" and use it in an unspecified German location, said the prosecutor's office. Their aim was "killing as many people as possible".
After police searched the suspects' houses in October 2016, Clement Baur went to France and his alleged Russian accomplice remained in Berlin.
An investigation made it possible to support evidence gathered two years ago that suggested the pair were preparing an attack in Germany.
Baur is also the subject of a similar investigation in France following his arrest in Marseille in April 2017, where he was thought to be planning a parallel attack to the one in Germany.
Magomed-Ali C is expected to appear in federal court on Thursday.