WASHINGTON

U.S. bomb experts are picking apart a sophisticated new al-Qaida improvised explosive device, a top Obama administration counterterrorism official said today, to determine if it could have slipped past airport security and taken down a commercial airplane.

Officials told The Associated Press a day earlier that discovery of the unexploded bomb represented an intelligence prize resulting from a covert CIA operation in Yemen, saying that the intercept thwarted a suicide mission around the anniversary of the killing of Osama bin Laden.

The device did not contain metal, meaning it probably could have passed through an airport metal detector. But it was not clear whether new body scanners used in many airports would have detected it. The device is an upgrade of the underwear bomb that failed to detonate aboard a jetliner over Detroit on Christmas 2009. Officials said 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.

John Brennan, President Barack Obama’s counterterrorism adviser, said today the discovery shows al-Qaida remains a threat to U.S. security a year after bin Laden’s assassination. And he attributed the breakthrough to “very close cooperation with our international partners.”

“We’re continuing to investigate who might have been associated with the construction of it as well as plans to carry out an attack,” Brennan said. “And so we’re confident that this device and any individual that might have been designed to use it are no longer a threat to the American people.”

On the question of whether the device could have been gone undetected through airport security, Brennan said, “It was a threat from a standpoint of the design.” He also said there was no intelligence indicating it was going to be used in an attack to coincide with the May 2 anniversary of bin Laden’s death.

Rep. Peter King, R-N.Y., chairman of the House Homeland Security Committee, said today that “a number of countries” provided information and cooperation that helped foil the plot. He said he had no information on the would-be bomber, but that White House officials had told him “He is no longer of concern,” meaning no longer any threat to the U.S.

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

There were no immediate plans to change security procedures at U.S. airports.

U.S. officials declined to say where the CIA seized the bomb. The would-be suicide bomber, based in Yemen, had not yet picked a target or purchased plane tickets when the CIA seized the bomb, officials said.

It was not immediately clear what happened to the would-be bomber.