BERLIN (AP) — German prosecutors said Friday they have charged a man with plotting an Islamic extremist attack in the Hamburg area around the time of last year's 20th anniversary of the Sept. 11, 2001 attacks in the United States.

The German-Moroccan dual citizen, identified only as Abdurrahman C. in line with German privacy rules, was in August. An indictment filed at the Hamburg state court charges him with preparing a serious act of violence and violating weapons laws.

It wasn't immediately clear when the case might go to trial.

Federal prosecutors alleged the suspect decided by January 2021 to carry out an attack in the Hamburg area, and that his model was the 2013 attack on the Boston Marathon.

He bought large quantities of chemicals as well as hundreds of screws and nuts that could be used for bomb-building, prosecutors said. To disguise his intentions, they added, he had the items delivered to a variety of addresses.

The suspect also allegedly tried to buy a hand grenade and a semiautomatic gun on the darknet, a part of the internet hosted within an encrypted network and accessible only through specialized anonymity-providing tools.

Three of the four militants who piloted the hijacked airliners used in the 9/11 attacks had lived and studied in Hamburg.