الجماعة الإسلامية المسلحة
During Abu Hamza's control, the mosque's attendance dropped. Most of the attendees were his followers. The mosque also became a meeting point for many radical Muslims. According to classified American documents released by WikiLeaks, Finsbury Park mosque previously served "as a haven" for Islamic extremists who subsequently fought against allied forces in Afghanistan. Al Qaeda operatives including "shoebomber" Richard Reid and Zacarias Moussaoui attended the mosque. In 2002, "The Guardian" reported that weapons training had taken place inside the building. On 11 September 2002, a conference was held at the mosque titled "A Towering Day in History" to praise the September 11 hijackers on the anniversary of the attack with the participation of Anjem Choudary, Abu Hamza, Omar Bakri Mohammed, Mohammad al-Massari and others. In the late 1990s, Abu Hamza and the mosque became the leading international spiritual reference supporting the Armed Islamic Group of Algeria (GIA) in the Algerian Civil War, at a time when the GIA was spurned even by most Salafi-jihadist groups for their massacres of civilians.