A woman has been arrested in the Yemeni capital on suspicion that she was involved in sending two explosive devices found on cargo planes bound for the United States, the president of Yemen said Saturday.

Security officials went to a house in Sanaa, the Yemeni capital, to arrest the woman a day after the plan was thwarted on Friday, President Ali Abdullah Saleh said. He told reporters the United States and the United Arab Emirates provided him with information that identified the woman as a suspect.

Yemeni security officials said the woman was detained as authorities search for a number of suspects believed to have used forged documents and ID cards that played a role in the plot. A Yemeni official said the woman was a medical student, and that her mother was also detained.

Dubai police confiscated a suspicious package aboard a U.S.-bound FedEx plane. The other package was found in the cargo area of the East Midlands airport, north of London near Nottingham, before it could be loaded onto an aircraft operated by the parcel company UPS.

Device was 'viable'

The device found at East Midlands could have brought down an aircraft if it had exploded, British Home Secretary Theresa May said Saturday.

"I can confirm that the device was viable and could have exploded," she told reporters after a meeting of the Cabinet Office Briefing Room Alpha, the government's emergency committee, which is known as Cobra.

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This image provided by CBS News shows a printer toner cartridge with wires and powder found Friday at the East Midlands airport, north of London, in a cargo package en route to the U.S. from Yemen. ((CBS News/Associated Press))

May said all air freight from Yemen, where the package originated, is now banned from entering the U.K. The U.S. Postal Service issued its own statement, saying it has "temporarily suspended acceptance of inbound international mail originating in Yemen."

The discovery of the devices, reportedly containing the chemical PETN packed in toner cartridges for computer printers, was made after a tip from Saudi intelligence officials.

"The target may have been an aircraft, and had it detonated, the aircraft could have been brought down," May said. "But we do not believe that the perpetrators of the attack would have known the location of the device when they planned for it to explode."

She added officials "have no information to indicate another terrorist attack is imminent."

U.S. investigators have said the mail bombs found in the United Arab Emirates and England were headed to two synagogues in Chicago.

Janet Napolitano, U.S. secretary of Homeland Security, said the plot "has the hallmarks of al-Qaeda." She said the search continues for other potentially dangerous packages shipped from Yemen.

Several U.S. officials said they were increasingly confident that al-Qaeda's Yemen branch, the group behind the failed Detroit airliner bombing last Christmas, was responsible.

U.S. President Barack Obama on Friday called the co-ordinated attacks a "credible terrorist threat."

A Yemeni security official said investigators there were examining 24 other suspect packages in Sanaa.

With files from The Associated Press