In an authoritative report, Quilliam, the think tank, said, "Mismanagement by the Prison Service is helping al-Qaeda gain recruits and risks strengthening jihadist movements."
Abu Qatada, described as Osama Bin Laden's right-hand man in Europe, has allegedly posted fatwas (religious decrees) on the Internet from Long Lartin jail, calling for jihad or holy war and the 'murder' of moderate Muslims, The Times reported.
Qatada is a radical Islamic cleric wanted on terror charges in Jordan. Like other jailed terrorist leaders, he is meant to be cut off from his supporters outside.
According to the report, Qatada and Adel Abdel Bary, leader of the UK branch of Egyptian Islamic Jihad, were able to smuggle out a series of fatwas legitimising attacks by al-Qaeda.
Qatada and Bary are two of about 100 Islamist terrorists in UK prisons.