Via the Guardian:
An al-Qaida operative accused of bombing two Christian churches and a luxury hotel in Pakistan in 2002 was at the same time working for British intelligence, according to secret files on detainees who were shipped to the US military's Guantánamo Bay prison camp.
Adil Hadi al Jazairi Bin Hamlili, an Algerian citizen described as a "facilitator, courier, kidnapper, and assassin for al-Qaida", was detained in Pakistan in 2003 and later sent to Guantánamo Bay.
But according to Hamlili's Guantánamo "assessment" file, one of 759 individual dossiers obtained by the Guardian, US interrogators were convinced that he was simultaneously acting as an informer for British and Canadian intelligence.
(source)
