British authorities are tracking almost 30 terrorist plots involving 1,600 individuals, the head of Britain's MI5 spy agency has said. Dame Eliza Manningham-Buller said many of the suspects were homegrown British terrorists plotting to kill with bombs and suicide attacks. In a speech released by the agency Friday, Manningham-Buller said MI5 had foiled five major plots since the July 2005 transit bomb attacks in London. Speaking to a small audience of academics in London on Thursday, Manningham-Buller said officials were "aware of numerous plots to kill people and to damage our economy." "What do I mean by numerous? Five? Ten?" she said. "No, nearer 30 that we currently know of." She added that, "Today we see the use of homemade improvised explosive devices, but I suggest tomorrow's threat will include the use of chemicals, bacteriological agents, radioactive materials and even nuclear technology."