LONDON - British police have charged eight people with plotting to blow up planes after police found bomb-making equipment, suicide notes and "martyrdom videos".
Three others were charged with terrorism-related offences by police investigating a suspected plot to attack several airliners flying from Britain to the United States.
US officials have said the plot to use liquid explosives could have caused a disaster on the scale of the September 11, 2001 attacks on US cities that killed nearly 3000 people.
Eight suspects - all British Muslims - were charged with conspiracy to murder and preparing acts of terrorism, prosecutor Susan Hemming said. They are accused of plotting to smuggle parts of homemade bombs onto planes, then build the bombs and detonate them.
The charges come 13 months after four British Islamist suicide bombers killed themselves and 52 other people during rush hour on public transport in London. Two left videos saying they acted to punish Britain for its foreign policy.
Peter Clarke, head of London police's anti-terrorist branch, said police had seized a huge amount of equipment and evidence, including "martyrdom videos" -- an apparent reference to testaments by would-be suicide bombers -- in 69 searches of houses, businesses, vehicles and open spaces.
They had found bomb-making equipment, chemicals including hydrogen peroxide, electrical components and documents, he said.
A 17-year-old man was charged with possessing items useful to a terrorist, including a book on home-made bombs, suicide notes, wills "with the identities of persons prepared to commit acts of terrorism" and a map of Afghanistan, prosecutors said.
Two other suspects -- including the mother of an eight-month-old baby -- were charged with failing to report the plot, Hemming said.
Of the 23 British Muslims arrested in the operation, 11 are being held pending a decision whether to charge them. Another woman was released without charge.
Clarke said the scale of the police investigation was immense and inquiries would "span the globe". The suspected plot was enormous and the inquiry would take many months, he said.
The unusually detailed account of the investigation given by police may be aimed at countering scepticism about the probe among some Muslims after several police blunders.
As many as 17 people are also being held in Pakistan over the suspected plot -- including at least two British nationals.
Police also seized more than 400 computers, 200 mobile telephones and 8000 memory sticks, CDs or DVDs.
The British government raised the threat level to "critical" for several days after the arrests, imposing tight restrictions on carry-on baggage by airline passengers that caused chaos at major British airports at the height of the summer holidays.
Although an initial ban on hand luggage and liquids being taken on board flights in Britain has been eased, airlines are still complaining at long turnaround times for security checks, and there have been calls for governments to foot the bill.