DUBAI, United Arab Emirates — One of two powerful bombs mailed from Yemen to Chicago-area synagogues traveled on two passenger planes within the Middle East, a spokesman for Qatar Airways said Sunday. The US said the plot bears the hallmarks of al-Qaida's offshoot in Yemen.The airline spokesman said a package containing explosives hidden in a printer cartridge arrived in Qatar Airways' hub in Doha, Qatar on one of the carrier's flights from the Yemeni capital San'a. It was then shipped on a separate Qatar Airways plane to Dubai in the United Arab Emirates, where it was discovered by authorities late Thursday or early Friday. A second, similar package turned up in England on Friday.RELATED:Netanyahu: We stand before a rising wave of terrorInside the head of a Yemenite al-Qaida mastermindIn Washington, President Barack Obama's counterterrorism adviser said Sunday that authorities "have to presume" there might be more potential mail bombs like the ones pulled from planes in England and the United Arab Emirates.Al-Qaida's offshoot in Yemen is suspected of mailing the bombs. The group was behind a failed bombing on a Detroit-bound airliner last Christmas that bore some of the same hallmarks as this plot.In Yemen on Sunday, police were searching for additional suspects after arresting a female computer engineering student suspected of mailing the packages and also detaining her mother. Both arrests were on Saturday.US officials said suspects in the plot include the bombmaker suspected of designing the explosive used in the failed Christmas airliner bombing. The bombmaker is a key operative in al-Qaida's offshoot in Yemen, Al-Qaida in the Arabian Peninsula (AQAP). Authorities were also looking at two language institutions in Yemen the plotters may have been associated with.