Surveillance
In Pakistan, a British man from Birmingham named Rashid Rauf is believed to have put plotters in touch with al-Qaeda's leadership. When Ahmed Ali, who was under police surveillance, returned from Pakistan in June 2006, investigators secretly opened his baggage. Inside they found a powdered soft drink—Tang—and a large number of batteries. It was enough to raise suspicions and in the following weeks, the police mounted the UK's largest surveillance operation, calling on an additional 220 officers from other forces.
Assad Sarwar (from High Wycombe) was seen buying items that did not appear to fit with his daily needs, and which may have had a potentially deadly context. On one occasion, surveillance officers watched him dispose of empty hydrogen peroxide bottles at a recycling centre. Sarwar and Ali were seen meeting in an east London park. When MI5 covertly entered a flat being used by Ali, they found what appeared to be a bomb factory. They left behind a camera and microphone, and on 3 August Ali and Tanvir Husain were seen constructing devices out of drink bottles. Surveillance officers watched Ali spend two hours in an internet cafe researching flight timetables.
Read more about this topic: 2006 Transatlantic Aircraft Plot