A German court has announced jail terms of up to nine years for four men convicted of belonging to the Islamist militant group al Qaeda, or for being its supporters, and for plotting an attack in Germany. The group of men, called the “Dusseldorf cell” by the German media, were arrested in 2011 in the cities of Dusseldorf and Bochum, three days before al Qaeda founder Osama bin Laden was killed.

The group was plotting to bomb a crowded place, followed by yet another bomb once rescue and emergency teams reached the spot, Reuters reported. Abdeladim El-K, a 30-year-old Moroccan, who was the leader of the group, is the highest ranking member of al Qaeda to have been tried in a German court, and was handed down a nine-year jail term. Prosecutors reportedly said that he had travelled to an al Qaeda training camp, on the border of Afghanistan and Pakistan in 2010, where he learned how to make explosives and use guns.

After returning to Germany, Abdeladim reportedly hired the three others -- Halil S., a German national; Amid C., a German-Iranian; and Jamil S., a German-Moroccan. The U.S. Secret Service reportedly tipped off German officials, leading to the men's arrests.

The group aroused suspicion after procuring large amounts of barbeque lighters, which contain the chemical used to make bombs. Jamil received a jail term of seven years while Amid was sentenced to five years in jail and Halil was jailed for four-and a half years, Deutsche-Welle, the German broadcaster, reported.