Would-be bomber was Saudi double agent

In an extraordinary intelligence coup,the double agent left Yemen last month,traveling by way of the UAE,and delivered both the innovative bomb designed for his aviation attack and inside information on the groups leaders,locations,methods and plans to the Central Intelligence Agency,Saudi intelligence and allied foreign intelligence agencies.

Officials said the agent,whose identity they would not disclose,works for the Saudi intelligence service,which has cooperated closely with the CIA for several years against the terrorist group in Yemen. He operated in Yemen with the full knowledge of the CIA but not under its direct supervision,the officials said.

After spending weeks at the centre of al-Qaedas most dangerous affiliate,the intelligence agent provided critical information that permitted the CIA to direct the drone strike Sunday that killed Fahd Mohammed Ahmed al-Quso,the groups external operations director and a suspect in the bombing of American destroyer USS Cole in 2000 in Yemen.

He also handed over the bomb,designed by the groups top explosives expert to be undetectable at airport security checks,to the FBI,which is analysing its properties. The agent is now safe in Saudi Arabia,officials said.

Representative Peter T. King,a New York Republican and chairman of the House Homeland Security Committee,called the bomb plot one of the most tightly held operations Ive seen in my years in the House.

A senior US official said the new device was sewn into custom-fit underwear and would have been very hard to detect even in a careful pat-down. Unlike the device used in the unsuccessful 2009 attack,this bomb could be detonated in two ways,in case one failed,the official said.

The main charge was a high-grade military explosive that undoubtedly would have brought down an aircraft, the official said.

Forensic experts at the FBIs bomb laboratory are assessing if the bomb could have evaded security measures revamped after the failed 2009 plot.