A woman has been arrested on suspicion of sending the two mail bombs found on cargo planes in the United Arab Emirates and the UK, Yemeni officials said.
Yemeni President Ali Abdullah Saleh said the US and the United Arab Emirates have provided him with information that identified the woman as a suspect. He said security forces had surrounded a house that was believed to be holding the woman.
A security official later said the woman had been arrested.
Home Secretary Theresa May earlier said the explosive device found hidden in a printer cartridge could have blown a plane out of the sky.
Following a Cobra meeting of the UK Government's emergency planning committee to discuss the security situation, she said the bomb was "viable" and the target may have been the aircraft itself.
A major international terror alert was sparked on Friday after printer cartridges with wires attached were found in cargo hubs at East Midlands Airport in the UK and in Dubai.
The packages originated in Yemen, a key front in the fight against terrorism, and are believed to have contained the powerful explosive PETN. This is the same chemical used by the so-called Underpants Bomber in the alleged plot to blow up a plane over Detroit on Christmas Day last year.
Police in Dubai said the device there contained an electric circuit linked to a mobile phone chip as well as the compound lead azide, which can be used in detonators.
Ms May said the initial investigation of the device was now complete. She said: "I can confirm the device was viable and could have exploded. The target of the device may have been an aircraft and, had it detonated, the aircraft could have been brought down.
"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. Our investigation remains sensitive. We will continue to work very closely with international colleagues to develop our understanding of what was planned and of course to bring to justice those responsible."
