SAN'A, Yemen — One of two powerful bombs mailed from Yemen to Chicago-area synagogues traveled on two passenger flights within the Middle East, a Qatar Airways spokesman said Sunday.

The U.S. said the plot bears the hallmarks of al-Qaida's offshoot in Yemen and has vowed to destroy the group.

The airline spokesman said a package containing explosives hidden in a printer cartridge arrived in Qatar Airways' hub in the capital Doha on one of the carrier's flights from Yemen.

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.

The airline spokesman disclosed the information on condition of anonymity in line with the company's standing policies on conversations with the media. He did not give any timeframe for the two flights in question — the airline operates daily passenger flights from Yemen.

For its part, FedEx said the shipment originated in Yemen and was confiscated at its shipping facility in Dubai.

The plot was the latest to expose persistent security gaps in international air travel and cargo shipping nearly a decade after the Sept. 11, 2001 attacks and showed terrorists appear to be probing those vulnerabilities.

"The security gap is now for things leaving Yemen," said Riad Kahwaji, head of the Dubai-based Institute for Near East and Gulf Military Analysis. "On the Yemeni side, they'll have a lot to answer for to regain their credibility."

In Washington, President Barack Obama's deputy national security adviser John Brennan said authorities "have to presume" there might be more potential mail bombs like the ones pulled from planes in England and the United Arab Emirates.

U.S. inspectors were heading to Yemen to monitor cargo security practices and pinpoint holes in the system. (AP)