WASHINGTON - (AP) - Despite the discovery of a sophisticated new al-Qaida airline bomb plot, congressional and security officials suggested no immediate need Tuesday to change to airport security procedures, which already subject shoeless passengers to intrusive pat-downs and body scans.

The CIA, with help from a well-placed informant and foreign intelligence services, conducted a covert operation in Yemen in recent weeks that disrupted a nascent suicide plot and recovered a new bomb, U.S. officials said.

Officials said the bomb represents an upgrade over the underwear bomb that failed to detonate aboard a jetliner over Detroit on Christmas 2009. This new bomb was also designed to be used in a passenger's underwear, but this time al-Qaida developed a more refined detonation system.

FBI experts are picking apart that non-metallic device to see if it could have slipped through security and taken down an airplane.

Meanwhile, U.S. officials sought to reassure the public that security measures at airports are strong. They said there are no immediate plans to subject airline passengers to new security screenings.

"I think people getting on a plane today should feel confident that their intelligence services are working, day in and day out," John Brennan, the top counterterrorism adviser to President Barack Obama, said on ABC's "Good Morning America."

Just last winter, al-Qaida's Yemen branch boasted that it had obtained a supply of chemicals used to make bombs. Chemicals can eliminate the need for electrical equipment to detonate explosives.

"Hence, no wearisome measures are taken anymore to attain the needed large amount of chemicals for explosives," the group wrote in its online magazine, "Inspire."

Working with an informant close to al-Qaida in Yemen, the CIA caught wind of the bomb plot last month, officials said, speaking on condition of anonymity to discuss intelligence matters.

The would-be bomber was supposed to buy a plane ticket to the United States and detonate the bomb inside the country, officials said.

Sen. Dianne Feinstein, D-Calif., who heads the Senate Intelligence Committee, told reporters Monday night that she had been briefed about an "undetectable" device that was "going to be on a U.S.-bound airliner."

Before the bomber could choose his target or buy his ticket, however, the CIA swooped in and seized the bomb.

The fate of the would-be bomber remains unclear. The plot was a reminder of the ambitions of al-Qaida in Yemen, the most active and dangerous branch of the terrorist group. While al-Qaida's core in Pakistan has been weakened over the past decade, instability in Yemen has allowed an offshoot group to thrive and set up training camps there. In some parts of the country, al-Qaida is even the de facto government.

Though analysis of the device is incomplete, U.S. security officials said they remained confident in the security systems that were in place.

CIA thwarts new al-Qaida underwear bomb plot