Airplane attack not considered part of larger plot: US official

WASHINGTON, Dec. 27 (Xinhua) -- There is no indication that the attempted bombing attack on a U.S.-bound airplane is part of a larger plot, U.S. Homeland Security Secretary Janet Napolitano said on Sunday.

"Right now we have no indication that it is part of anything larger. But obviously the investigation continues," Napolitano told CNN's "State of the Union" program.

Umar Farouk Abdulmutallab, a 23-year-old Nigerian attempted to destroy an airplane bound for Detroit, Michigan, claimed that he has ties with al-Qaida, the terrorist group that took responsibilities with the Sept. 11, 2001 attacks.

However, Napolitano said it would be too early to make any conclusion on that.

"Right now, that is part of the criminal justice investigation that is ongoing, and I think it would be inappropriate to speculate as to whether or not he has such ties," she said.

She also said there was "no suggestion" that authorities in Amsterdam had improperly screened the Nigerian suspect, officially charged on Saturday by U.S. authorities with trying to destroy an American plane.

"What we are focused on is making sure that the air environment remains safe, that people are confident when they travel," she added.

U.S. authorities didn't raise the terrorism alert status from its current "orange" level, but warned that passengers may notice additional screening and security measures at airports in the coming days.

On Friday, Abdulmutallab attempted to ignite an explosive device attached to his body on Delta/Northwest Flight 253 from Amsterdam, the Netherlands, to Detroit, but was subdued by other passengers.