Yemen police on Sunday released a university student arrested the day before on suspicion of having links to two parcels containing explosives found on US-bound flights, a security source said.
Hanan Mohamed al-Sanawy, 22, a computer science student "was released after investigations showed that she was the wrong person," the source told the German Press Agency dpa.
Yemen said earlier it had arrested Hanam al-Sanawy based on a US intelligence tip.
The two packages, later intercepted in Dubai and Britain, had been sent from the Yemeni capital of Sana'a.
Qatar Airways confirmed Sunday that it had shipped on two passenger planes a parcel that originated in Yemen and was found to contain explosive materials.
The parcel first went from Sana'a to Doha and then on a second plane to Dubai where it was seized, after what officials said were intelligence tip-offs.
The airline said that responsibility for cargo inspections lay with the country of origin, in this case Yemen, and not with transit countries or carriers.
The second bomb parcel was discovered on Friday in Britain's East Midlands Airport, where it had arrived via the German city of Cologne.
Germany has banned arrivals of all air cargo from Yemen, Transport Minister Peter Ramsauer said.
The White House's top counterterrorism official said the same individual was likely to be behind several bombs originating from Yemen.
"I think the indications are right now based on the forensics analysis that it's an individual who has been responsible for putting these devices together, the same (person)," John Brennan told the US television channel ABC.
He was referring to the latest packages as well as a bomb which was used in an assassination attempt on Saudi Arabia's top counterterrorism official and the Christmas Day attempt last year to blow up an airliner over Detroit.
US officials have said Saudi-born bomb-maker, Ibrahim Hassan al- Asiri, is linked to the case, though they say other people are also involved. He is said to have been linked to numerous attacks originating in Yemen.
Brennan said on various US Sunday morning television programmes that authorities were still searching for other packages that might contain explosives, saying that in his mind the "sophistication" of the two intercepted packages so far indicate that "it was an Al Qaeda in the Arabian Peninsula effort".
The Yemeni government continued to stress its resolve to fight against terrorism "despite hype over the explosive packages", the state-run news agency SABA reported.
"I want to affirm that there are unfortunately different and exaggerating reports on the issue serving Al Qaeda and at the same time harming counterterrorism efforts," Yemeni Information Minister Hassan al-Lawzi said.
Meanwhile, the debate over the economics of security was revived, as the British pilots union charged that a focus of resources on security for passenger planes "left the door open" for attacks on other sectors of the aviation industry, including cargo.
British and US officials have said that the parcels intercepted could have exploded on board a plane.