Yemeni security forces were on Sunday searching for suspects who posted parcel bombs on two US-bound flights after arresting a woman over an alleged Al-Qaeda plot that sparked a global air cargo alert.
The woman was detained on Saturday after being tracked down through a phone number on a receipt for the explosives-filled packages, which were found on freighter jets in Britain and Dubai the day before, Yemeni officials said.
The Yemeni authorities have also launched a wider search for more suspects believed to be linked to the Yemeni branch of Al-Qaeda and the mail bombs, local media reports said.
A string of countries further boosted their cargo security measures as British Prime Minister David Cameron said the bomb found in his country was apparently designed to blow the aircraft out of the sky.
"Yemeni security forces arrested a woman suspected of sending two parcel bombs," Yemen's defence ministry said. President Ali Abdullah Saleh said security services "received information that a girl has sent the parcels from the two cargo companies," apparently referring to UPS and FedEx, the US firms through which the parcels were sent. US officials have said the packages were addressed to synagogues in Chicago.
The woman, who medicine student at Sanaa university and whose father is a petroleum engineer, was held with her mother after her mobile phone number was found on the receipt for the parcel bombs, a Yemeni security official said. Yemeni officials also said they were examining 26 other seized packages. US President Barack Obama has made it clear he suspects the involvement of Al-Qaeda in the Arabian Peninsula (AQAP), the Yemen-based branch of Osama bin Laden's extremist network, vowing to wipe out the organisation.
In Britain, Cameron said of the bomb discovered at East Midlands airport in central England that authorities "believe that the device was designed to go off on the airplane", possibly over British soil. Dubai police said the parcel bomb found there bore the "hallmarks of Al-Qaeda". It involved the high explosive PETN hidden inside a computer printer with a circuit board and mobile phone SIM card attached.
Britain's Sunday Telegraph newspaper and The Washington Post said investigators were focusing on a Saudi Al-Qaeda explosives expert based in Yemen, 28-year-old Ibrahim Hassan al-Asiri. Asiri's brother Abdullah attempted to kill the Saudi deputy interior minister in August 2009 in a suicide attack that reportedly involved explosives concealed inside his own body.
Yemen is also the hiding place for US-born radical cleric Anwar al-Awlaki, who is on a US list of terrorism supporters for alleged links to plots including a failed bombing of an airliner heading for Detroit on Christmas Day 2009. PETN, or Pentaerythritol tetranitrate, was used in that attempt by would be "underpants bomber" Farouk Abdulmutallab and also in 2001 by attempted shoe-bomber Richard Reid.
The New York Times reported that investigators said the bombs were expertly constructed. The one discovered at the Dubai airport was concealed in a Hewlett-Packard desktop printer, with high explosives packed into a printer cartridge to avoid detection by scanners, it said. "The wiring of the device indicates that this was done by professionals," the paper quoted an official involved in the investigation as saying. "It was set up so that if you scan it, all the printer components would look right."
The bomb discovered in Britain was also hidden in a printer cartridge, the report said. A rabbi at one of the Chicago synagogues allegedly targeted in the plot said the community's website was visited dozens of times recently by individuals from Egypt, The Wall Street Journal reported.
The cargo scare presented a new twist as Western authorities have usually focused on dangers to passenger jets following the September 11, 2001 attacks, when Al-Qaeda hijacked planes and struck targets in New York and Washington.
Germany and France announced they would no longer accept air freight from Yemen. Australia said it would screen all air cargo from Dubai and Doha. German Chancellor Angela Merkel, in Britain on an informal visit, was due to discuss counter-terrorism cooperation during talks with Cameron on Sunday, Downing Street said.
Experts said the bomb plot highlighted the gaps in air cargo security but also the growing innovation of militant groups.
"This is the first time that a terrorist group has used a US air freight company to transport a parcel containing explosives and a detonator," Jean-Charles Brisard, a global consultant on terror groups sa