Yemeni authorities arrested a woman Saturday and searched for other suspects linked to al-Qaida's Persian Gulf faction in the plot to mail bombs powerful enough to down a cargo plane.
Officials said the woman was detained as part of a widening search for people believed to have used forged documents and ID cards in the plot thwarted Friday. Authorities on three continents scrambled to check planes from Philadelphia to central England, recovering two live explosive devices addressed to two synagogues in Chicago.
The dragnet in Yemen and the results of a preliminary investigation into one of the bombs in Britain reflected the seriousness of a plot that investigators said bore all the hallmarks of al-Qaida. Yemeni officials said the suspects were believed linked to al-Qaida in the Arab Peninsula, the group's affiliate in the Persian Gulf.
Yemen's president, Ali Abdullah Saleh, told reporters that the U.S. and the United Arab Emirates had provided information that helped identify the woman as a suspect.
Two security officials told The Associated Press the woman was arrested in the al-Rawdah district near the airport in San'a, Yemen's capital. "According to our information, a woman has sent the packages through the agents (companies)," Saleh said in his briefing.
One of the Yemeni officials, a member of the country's anti-terrorism unit and close to the Yemeni team probing the case, said the other suspects had been tied to al-Qaida's faction in Yemen.
Several U.S. officials said they increasingly are confident of the involvement of al-Qaida's Yemen branch, the group behind the failed Detroit airliner bombing last Christmas. A Nigerian-born passenger tried to set off a bomb packed with PETN, an industrial explosive that was the same potent ingredient used in the mail bombs found Friday. But the suspect's underwear detonator failed to operate properly.
U.S. officials said al-Qaida's explosives expert in Yemen, Ibrahim Hassan al-Asiri, was the likely suspect behind the bombmaking. Al-Asiri helped make the bomb used in the Christmas attack and another PETN device used in a failed suicide attack against the top Saudi counterterrorism official last year, officials said.
A U.S. official also said both bombs seized on Friday were attached to power supplies, a further indication that they were viable. All the officials spoke on condition of anonymity because of the sensitivity of the investigation.
U.S. investigators said the mail bombs found in the UAE and England were headed to two synagogues in Chicago. But British Home Secretary Theresa May said it was possible that the cargo plane carrying the package from Yemen may have been the target, too.
A second package was discovered in Dubai, where white powder explosives were discovered in the ink cartridge of a printer, police said in a statement. The device was rigged to an electric circuit, and a mobile phone chip was hidden inside the printer, the statement said.
The bombs were constructed to be activated by cell phone and a timer, but investigators have not found either of those devices, said Rep. Jane Harman, D-Calif., a member of the House Homeland Security Committee who was briefed on the investigation.
Officials continue to investigate whether the bomb would have worked, a U.S. official said.
Yemeni authorities were checking dozens more packages in the search for the terrorists who sent the bombs, though there were no signs of additional explosives. Authorities questioned cargo workers at the airport as well as employees of the local shipping companies contracted to work with FedEx and UPS, a Yemeni security official said.
The White House said President Barack Obama's counterterrorism adviser, John Brennan, called Yemen's president and made clear that the U.S. was ready to help his government against al-Qaida. The U.S. already assists Yemen with air strikes and other counterterrorism information.
U.S. officials temporarily banned all cargo shipments from Yemen. An employee at the UPS office in Yemen said the office had been instructed not to receive any packages for delivery for the time being. The U.S. Postal Service has decided not to accept any inbound mail from Yemen for now.
The U.S. has FBI, military and intelligence officers stationed in the country to conduct an inquiry. There are only a few international shipping locations in the impoverished Arab nation, but U.S. officials worried that record keeping would be sparse and investigators would have to rely more on intelligence sources to identify the would-be bombers.
Yemen is home to the radical U.S.-born Muslim cleric Anwar al-Awlaki, who's linked to the Christmas attack and has inspired other terrorists with his violent message. Also hiding in Yemen is Samir Khan, an American who declared himself a traitor and helps produce al-Qaida propaganda.
Intelligence officials were onto the suspected plot for days, officials said. The packages in England and Dubai were discovered after Saudi Arabian intelligence picked up information related to Yemen and passed it on to the U.S., two officials said.
U.S. intelligence officials warned last month that terrorists hoped to mail chemical and biological materials as part of an attack on the United States and other Western countries. The alert came in a Sept. 23 bulletin from the Department of Homeland Security that was obtained by The Associated Press.
Since the failed Christmas bombing, Yemen has been a focus for U.S. counterterrorism officials. Before that attack, the U.S. regarded al-Qaida's branch there as primarily a threat in the region, not to the United States.
The Yemen branch, known as al-Qaida in the Arabian Peninsula, has since become a leading source of terrorist propaganda and recruiting. Authorities believe about 300 al-Qaida members operate in Yemen.
Adam Goldman in Washington, Raphael G. Satter in London, Ahmed al-Haj in San'a, Yemen, and Adam Schreck in Dubai contributed to this report.
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