LONDON -- Authorities warned Britons to remain vigilant yesterday , saying 24 separate terrorism probes under way showed they could still be in the crosshairs of Islamic militants even after security forces foiled an alleged plot to bring down planes heading to the United States.
Tempers flared at the airports, as hundreds of flights were canceled and lengthy security checks caused some passengers to miss their flights.
Home Secretary John Reid, Britain's home secretary, said authorities were conducting two dozen separate counterterrorism investigations in the country , and there was no guarantee the government would be able to thwart every plot.
British police questioned 22 of the suspects in detention yesterday , but authorities remained silent on what, if anything, they have learned.
Without any briefings from police or government officials, the British press was left to speculate on a range of theories.
The Sunday Mirror tabloid asserted that a female suspect in custody may have been planning to use her baby as a diversion to smuggle a bomb onto the plane, but it did not name its sources. The Sunday Times reported that one of those in custody was believed to be Al Qaeda's leader in Britain, but it did not say which suspect. And The Independent yesterday cited security sources as saying terrorists were planning an ``Apocalyptic wave" of attacks.
There was plenty of time for travelers to soak up those theories as they waited in long lines at all the country's airports, particularly London's Heathrow and Gatwick.
Almost a third of flights out of Heathrow were canceled yesterday -- the airport handles about 1,250 flights a day -- and the ban on all carry-on items remained in effect.
``It's disgusting. They don't have a system," Jenny Chua, who was waiting yesterday at Heathrow for a flight to Singapore, told The Guardian . ``We've been trying to call for days and they don't have enough staff."
Some airlines have accused the British Airports Authority -- which operates seven of the country's major airports -- of being unable to cope with the new anti-terror security requirements. Others appealed to the British government to use police and army reservists to speed up searches at overloaded airport security checkpoints.
``If we the industry and the government don't work together to have sensible security . . . we are going to hand these extremists a terrific PR success," Michael O'Leary, the chief executive of budget airline
British Airways acknowledged that some people were missing flights yesterday because they were stuck in security lines.