The United States has foiled a plot by Al-Qaeda's branch in Yemen to blow up an airliner and recovered an explosive device, officials said Monday, stressing the public was never in danger.
"The device was for use by a suicide bomber on an airliner," a US counterterrorism official told AFP on condition of anonymity.
The plot hatched by Al-Qaeda in the Arabian Peninsula was uncovered at an early stage and represented a "success story" for US authorities working closely with allies, he added.
"At no point were any airlines at risk," the official said, as news of the plot was revealed just days after the first anniversary of the killing of Al-Qaeda chief Osama bin Laden by US commandos at his Pakistan hideout.
The bomb had "notable differences" from the explosive employed in a failed attempt also linked to the Al-Qaeda affiliate to blow up a US-bound airliner on Christmas Day 2009 using plastic explosives hidden in a Nigerian man's underwear, the official said.
According to the FBI, the improvised explosive device was seized abroad and was currently in its possession. Agents were "conducting technical and forensics analysis on it."
"Initial exploitation indicates that the device is very similar to IEDs that have been used previously by Al-Qaeda in the Arabian Peninsula (AQAP) in attempted terrorist attacks, including against aircraft and for targeted assassinations," the FBI statement added.
The bomb was "a non-metallic device," the counterterrorism official said, presumably to avoid detection by airport security. "This suggests AQAP is adapting its methodology, its tactics et cetera."
President Barack Obama was briefed about the plot in April and was told by his deputies that lives were never in danger, said Caitlin Hayden, deputy spokeswoman for the National Security Council.
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"While the president was assured that the device did not pose a threat to the public, he directed the Department of Homeland Security and law enforcement and intelligence agencies to take whatever steps necessary to guard against this type of attack," she said in a statement.
AQAP has been linked to the 2009 Christmas plot in which a bomb hidden in an attacker's underwear failed to detonate on a plane bound for Detroit.
And it is also suspected of having a hand in a 2010 attempt to blow up cargo planes heading to the United States with explosives concealed in printer cartridges.
The latest plot "demonstrates our adversaries' interest in targeting the aviation sector," the Department of Homeland Security said, adding it would continue "to employ a risk-based, layered approach to ensure" public safety.
"These layers include threat and vulnerability analysis, prescreening and screening of passengers, using the best available technology, random searches at airports, federal air marshal coverage and additional security measures both seen and unseen," DHS spokesman Matt Chandler said.
Security at airports and on US-bound airliner flights have been tightened since the failed Christmas Day bombing, when intelligence agencies were heavily criticized for failing "to connect the dots" among all the intelligence data available.
Nigerian Umar Farouk Abdulmutallab was sentenced in February to four consecutive life sentences for his botched attempt to blow up Northwest Airlines Flight 253 as it approached Detroit.
In court, Abdulmutallab declared he was "proud to kill in the name of God" as he defended his botched attempt to kill the 289 people on board the flight that originated in Amsterdam.
Hijacked airliners were also used to carry out the September 11, 2001 attacks on New York, Washington and Pennsylvania in which almost 3,000 people were killed.