The unidentified double agent, who works for the Saudi intelligence service, persuaded al-Qaida bomb makers in Yemen to give him a new bomb, designed to be undetectable at airport security checks, as well as vital inside information about the group's leaders, locations, methods and plans, officials told several news organizations.
The agent funneled the information to U.S., Saudi and allied foreign intelligence agencies, the officials said.
One key piece of information led to the CIA's Sunday drone attack that killed senior al-Qaida militant Fahd al-Quso, 37, a suspect in the 2000 bombing of the USS Cole warship in Yemen, U.S. officials said.
That suicide bombing killed 17 U.S. sailors and injured 39 others.
The informant -- who U.S. officials said operated in Yemen with the full knowledge of the CIA but not under its direct supervision -- handed over the new bomb to the FBI, which was analyzing its properties at its Quantico, Va., laboratory, officials said.
The informant is safe in hiding at an undisclosed Saudi location, officials said.
The bomb is a more advanced version of an underwear bomb used in a failed 2009 Christmas Day attempt to take down a Northwest Airlines flight with 290 people flying to Detroit from Amsterdam, The Netherlands, officials said.
It is believed to have been designed by Ibrahim Hassan al-Asiri, reputed to be the top explosives expert in al-Qaida's Yemeni branch, who officials allege designed the Christmas Day bomb as well, they said.
Asiri, 31, remains at large and is a CIA drone target in Yemen, The Wall Street Journal reported.
The sting operation to steal the bomb and Sunday's drone strike "are part of the same operation," House Homeland Security Committee Chairman Peter King, R-N.Y., told reporters Tuesday.
King called the bomb plot "one of the most tightly held operations I've seen in my years in the House."
He added he was told U.S. government officials planned to investigate the source of the leak that exposed the al-Qaida plot and double-agent scheme, which he said could endanger future counterterrorism operations.
"We are talking about compromising methods and sources and causing our partners to be leery about working with us," he said.
The CIA declined to comment.
The Saudi Embassy in Washington had no immediate comment.
Yemeni officials said they weren't informed about the operation.
The U.S. Transportation Security Administration repeated a security message Tuesday for airlines and foreign governments, officials said.
The message warned the Yemeni al-Qaida affiliate still intended to attack the United States, probably using commercial aviation, and warned TSA agents to look out for explosives in cargo, concealed in clothing or surgically implanted.