The CIA thwarted an ambitious plot by Al Qaeda's affiliate in Yemen to destroy a U.S.-bound airliner using a bomb with a sophisticated new design around the one-year anniversary of the killing of Osama bin Laden, The Associated Press has learned.

The plot involved an upgrade of the underwear bomb that failed to detonate aboard a jetliner over Detroit on Christmas 2009, according to FOX News. This new bomb was also designed to be used in a passenger's underwear, but this time Al Qaeda developed a more refined detonation system, U.S. officials said.

The FBI is examining the latest bomb to see whether it could have passed through airport security and brought down an airplane, officials said. They said the device did not contain metal, meaning it probably could have passed through an airport metal detector. But it was unclear whether new body scanners used in many airports could have detected it.

The would-be suicide bomber had not yet chosen a target or bought his plane ticket when the CIA seized the bomb, FOX News says. It is currently unclear what happened to the alleged bomber.

The operation unfolded even as the White House and Department of Homeland Security assured the American public that they knew of no Al Qaeda plots against the U.S. around the anniversary of bin Laden's death. The AP learned about the thwarted plot last week but agreed not to publish it immediately because the sensitive intelligence operation was still under way.

U.S. officials, who were briefed on the operation, insisted on anonymity to discuss the case, FOX News reports.