Story highlights Saudi intelligence was involved "from A to Z," a source says

The Saudi intelligence chief oversaw the operation, a source says

The bomb-maker rectified earlier mistakes, a source says

The leak about a mole involved in the operation is "unfortunate," a U.S. lawmaker says

The agent who penetrated al Qaeda in the Arabian Peninsula and returned from Yemen with the group's new "airline bomb" was always under Saudi control and was not a double-agent, two sources briefed by Saudi counterterrorism officials have told CNN.

One source told CNN that the device was recovered around April 20, more than a week before the first anniversary of the killing of Osama bin Laden, and was then handed over to the United States for forensic analysis.

One source said that from the very beginning, the infiltrator was working for Saudi intelligence. The other said Saudi intelligence was involved "from A to Z." The source added that the agent involved had moved in the "jihadist orbit" in Saudi Arabia before being recruited.

The agent was sent to Yemen "months and months" ago, when Saudi sources in Yemen reported indications that al Qaeda in the Arabian Peninsula, or AQAP, might be again preparing a plot against U.S. aviation, one source said.

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These were the first indications "that al Qaeda might be trying again," according to one source, after the Christmas Day 2009 underwear bomb plot and the laser-printer bombs dispatched from Yemen in October 2010.

The whole operation was personally overseen by Prince Mohammed bin Nayef, the head of Saudi counterterrorism, one source said.

Initial reports had not revealed the extent of Saudi involvement.

At one point, the Saudi agent reported that a device was being built, and the Saudis then informed the United States, according to one of the latest sources, who spoke to CNN on condition of anonymity, citing the sensitivity of the information.

The agent then received training on the device from AQAP instructors.

According to one source the device contained PETN explosive, the same explosive used in previous attacks by AQAP's master bomb-maker Ibrahim al Asiri.

Describing the bomb, one source said it was smaller than previous bombs made by al-Asiri.

The other said it contained an amount of explosive similar to that hidden inside laser printers that were sent from Yemen in October 2010 . The printer devices contained 300 to 400 grams of explosive and had a larger amount of high explosive than carried in the Christmas Day flight from Amsterdam to Detroit.

One source told CNN the device was designed to be worn in clothing. There has been no confirmation from other sources of that detail. The source said the device was "more advanced" than the underwear device, as al-Asiri was trying to rectify past mistakes. The device in 2009 failed to detonate, apparently because the detonation charge failed to set off the PETN explosives.

The source added that AQAP bomb-makers apparently believed that in the case of the Christmas Day plot they had got the initiator mechanism wrong, and that the mistake in that case was to mix acids slowly in an effort to begin the detonation.

Homeland Security Secretary Janet Napolitano told reporters Tuesday that the device is "similar to the underwear bomber of 2009, but an evolution to that."

Saudi intelligence had hoped that their agent would be able to get information about al-Asiri's whereabouts, but the agent did not meet al-Asiri, one source said.

One source cautioned: "Even if al-Asiri is eventually killed, we should not celebrate, because he has trained many people."

It is still unclear how the device left Yemen. One Arab source familiar with the investigation said he assumed it had been carried on a plane, which would raise troubling questions about airport security in the capital, Sanaa. But another hinted that it had been carried overland, in the possession of the Saudi mole.

One source said Saudi counterterrorism officials were upset that details of the operation had emerged in the United States because they had a network of agents inside AQAP who could be compromised by leaks from Washington.

The sources also questioned suggestions that the infiltrator's information led to the successful drone strike over the weekend that targeted Fahd al-Quso, a leading figure in AQAP. The Saudi agent did not meet al-Quso while in Yemen, according to one source.

The sources said AQAP has better resources than previously and is using the safe haven created in southern Yemen to good effect. The group has developed laboratories and is extending training in chemistry and bomb-making, he said.

"At the moment they can operate in relative freedom," the source said.

The Saudi concern over the leak of information about the mole infiltrating AQAP was echoed by the chairman of the U.S. House Homeland Security Committee.

"It's really, to me, unfortunate that this has gotten out, because this could really interfere with operations overseas," Rep. Peter King of New York told CNN's Anderson Cooper on Tuesday. "My understanding is a major investigation is going to be launched because of this."

A senior administration official told CNN that officials were debating whether to release photographs of the device to law enforcement agencies.

On one side of the argument, Transportation Safety Administration screeners and law enforcement might more easily identify any similar devices made as part of the same plot, the official said.

But officials were reluctant to do so out of concern that the photographs would be leaked to the news media and that the would-be bombers would learn what law enforcement knows -- and might not know -- about the bomb's workings.

John Brennan, the chief White House counterterrorism adviser, who told ABC's "Good Morning America" on Tuesday that officials believe redundant security systems would have prevented any airline bombing attempt from succeeding, but analysts were studying the device to see whether security procedures should be adjusted.

"We're trying to make sure that we take the measures that we need to prevent any other type of IED, similarly constructed, from getting through security procedures," Brennan said.

A Department of Homeland Security spokesman said authorities have "no specific, credible information regarding an active terrorist plot against the U.S. at this time."

But another U.S. official told CNN, "We are not ready to say the threat stream is over. We believe external plotting continues."