Sources tell CBS News that British police have foiled a plot to blow up an airliner en route from London's Heathrow Airport to the U.S. Sajid Badat, a Pakistani Briton, was arrested in his hometown of Gloucester last week during a series of police raids across Britain.
Badat, 24, was charged Wednesday with conspiring with Richard Reid, the so-called "shoe bomber," and "others unknown" to cause an explosion "likely to endanger life" between September 1, 2001 and November 28, 2003.
He is also charged with two lesser offenses of "possessing explosives."
Shortly after the arrest, Home Secretary David Blunkett said the security services and police believed the suspect had "connections with the network of al Qaeda groups."
"We would not have taken these steps had we not believed that this individual posed a very real threat to the life and liberty of our country," Blunkett told CBS News Correspondent Tom Fenton.
London police commissioner Sir John Stevens said Wednesday the force is on a heightened state of terrorist alert.
Reid was sentenced to life in prison for a Dec. 22, 2001, bombing attempt aboard a Paris-to-Miami flight. When he pleaded guilty in October 2002, Reid said he was a member of al Qaeda, pledged his support to Osama bin Laden, and declared himself an enemy of the United States.
Reid had tried to ignite plastic explosives hidden in his shoes on American Airlines Flight 63. Prosecutors said there was enough plastic explosives in his shoes to blow a hole in the fuselage and kill all 197 people aboard.
Badat was one of more than a dozen people arrested and questioned under anti-terrorism laws in the past week, but police said they were not linked.
Ibrahim Master, chairman of the Lancashire Council of Mosques, said last week that the suspect had been a student at the College of Islamic Knowledge and Guidance in Blackburn, northern England.
An Algerian national, Noureddinne Mouleff, was charged earlier Wednesday with terrorism and fraud offenses.
Mouleff, 36, who lives in southern England, was charged under the Terrorism Act provision that cites "possession of items or articles connected to the commission, preparation or instigation of terrorism."
Appearing at Bow Street Magistrates Court in central London, Mouleff was also charged with conspiring with others to defraud banks of $127,500. His bail application was rejected and he was ordered to attend a Dec. 10 hearing at the Old Bailey criminal court.
Terrorism experts say Badat's arrest was a major success. But it's also a cause for alarm.
"The logical conclusion has to be that the terrorist handlers of Richard Reid, as also this British Pakistani, may have been grooming a number of sleeper suicide bombers and this raises the possibility: How many others are out there?" asks M.J. Gohel of the Asia-Pacific Foundation.
Experts say the real problem for security forces is that there is no single person directing potential atrocities. There are a number of autonomous groups, based in a number of countries. If one cell is destroyed, there are other unconnected cells still out there.
The Sunday Times this week reported that security services feared a Christmas bombing campaign by al Qaeda terrorists — simultaneous attacks on such soft targets as shopping centers. It said unidentified security sources said suspects under surveillance had carried out possible reconnaissance or "dummy runs" for attacks on commercial centers.
The report could not be confirmed, and police repeated their statement that they had no specific intelligence, but advised the public to be alert to any potential threat.
Director-general of the MI5 security service Eliza Manningham-Buller said in October that the threat of attack by Islamic terrorists was at a high level. She described a kind of "sleeper" terrorist who might be living in Britain — networks of individuals sympathetic to the aims of al-Qaida that blend into society. "Some of these individuals are in the U.K," she said.
Terrorist attacks on British targets in Turkey two weeks ago killed at least 27 people and wounded hundreds.
Britain has advised its nationals in Saudi Arabia to maintain a high level of vigilance, particularly in places frequented by foreigners such as hotels, restaurants and shopping malls.
A Nov. 8 suicide bombing at a Riyadh housing compound was preceded by warnings of a pending terrorist attack issued by the Australian, British and U.S. embassies in Riyadh. Seventeen people were killed.
© 2003 CBS Interactive Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.