British officials were to decide at a closed-door hearing yesterday whether to charge 11 more suspects in the alleged plot to blow up several trans-Atlantic airliners as British investigators gather evidence for a trial that may not begin for another two years.

The hearing, open only to a district judge, investigators and lawyers, is the next step as detectives attempt to piece together thousands of bits of information to back their claims of thwarting a global terror plot.

The suspects could be charged, freed or ordered to remain in custody without charge. On Monday, 11 other people were charged in the alleged plot to blow up as many as 10 US-bound airliners with liquid-based explosives. Eight men were charged with two counts each of conspiracy to commit murder and preparing to commit terrorism.

Two others, including a woman, where charged with failing to disclose information that could help prevent a terrorist act. A third person, a teenager, was charged with possessing material that could be used to prepare a terrorist act. The 11 suspects yet to be charged have been in custody since August 10.

On Tuesday, Peter Clarke, who oversees the Metropolitan Police’s anti-terrorism unit, said months of surveillance had produced “significant video and audio recordings” regarding the alleged plot. He said investigators also found bombing-making chemicals, including hydrogen peroxide, as well as electrical components.

In addition, investigators seized maps of Afghanistan, suicide notes from willing terrorists, books on explosives and more than 8,000 items of data storage, such as compact discs, DVDs and memory sticks, officials said. Investigators said the evidence, including fingerprints, DNA and handwriting, was still being examined. British officials have said the plot involved the manufacture of explosives that would be assembled and detonated on board airliners.

British investigators have not revealed if the suspects are linked to al-Qaida. Officials in Pakistan have linked people arrested there over the alleged conspiracy to al-Qaida militants.