The report came a day after US television network ABC warned of an imminent attack against Americans in Germany by an al Qaeda cell.
The group, consisting of two German converts to Islam and three German citizens of Turkish origin, belongs to an organisation with ties to al Qaeda called Islamic Jihad Union, news magazine Focus reported, quoting German police and prosecutors.
The men were trained in Pakistan and had already created farewell videos, commonly made by suicide bombers before an attack, the magazine reported in its edition to go on sale Monday.
ABC News said there was particular concern over possible attacks at the Stuttgart headquarters of the US European Command in southwestern Germany.
