PARIS - The terror alert that caused the cancellation of several trans-Atlantic flights this weekend was based partly on intelligence that al-Qaida might use chemical, biological or radiological weapons in an aviation attack, a U.S. official familiar with the case said yesterday.
"A chemical, biological or 'dirty bomb' attack has always been a concern with regard to aviation," said the U.S. official, speaking on condition of anonymity. "And that was one of the concerns in this case."
After the U.S. government warned Saturday of "a specific and credible threat," British Airways canceled two London-to-Washington round trips and a London-to-Miami flight, while Air France grounded two Paris-to-Washington flights. Those flights were scheduled for yesterday and today.
Yesterday, Continental Airlines canceled a flight from Washington to Houston that was scheduled to arrive while the Super Bowl was being played at Reliant Stadium, about 28 miles from the international airport. That action came a day after Continental grounded a flight from Glasgow, Scotland, to Los Angeles.
"There was specific threat information on Continental Flight 1519 from Washington to Houston, and that information was shared with the airline," said Suzanne Luber, a spokeswoman for the Department of Homeland Security in Washington. "We don't have any information that it was connected to the Super Bowl. It was a specific threat related to the flight number and the date, but not as to what kind of threat."
Since December, law-enforcement and intelligence agencies in the United States and Europe have detected signs that terrorists were plotting an airborne attack.
U.S. authorities put out an alert warning about smuggled explosives after the arrest in December of a British suspect who allegedly rigged plastic explosives in a pair of socks, a device he allegedly intended to use to sneak a bombmaking kit past airport security.
But a flurry of intelligence in December that led to eight cancellations of U.S.-bound flights, including six Paris-to-Los Angeles trips before Christmas, also made reference to unconventional weapons, according to the senior U.S. official.
"The alert about flights did not exclude a possible chem, bio or radioactive attack last time, in December," the official said. "But this dimension of the threat seems to be more developed in the intelligence this time."
The possibility of smuggling a biological agent onto an airplane poses a distressing new danger, a key U.S. senator said yesterday.
"Nobody has any idea about what to do about them [biological agents] on an airplane or on the ground," Sen. John D. Rockefeller IV, a West Virginia Democrat, said on Fox News Sunday.
The Los Angeles Times is a Tribune Publishing newspaper. Times staff writer David G. Savage in Washington contributed to this report.