Ammon News - AMMONNEWS - The US has ordered tighter security at some foreign airports offering direct flights to the United States, the Homeland Security secretary has said.

Homeland Security Secretary Jeh Johnson said he directed the Transportation Security Administration to put more security measures in place at some foreign airports that have non-stop flights to the US.

"Aviation security includes a number of measures, both seen and unseen, informed by an evolving environment," Johnson said.

"We will continue to adjust security measures to promote aviation security without unnecessary disruptions to the traveling public".

The US shared "recent and relevant" information with foreign allies, Johnson said.

Intelligence officials are concerned about new al-Qaeda efforts to produce a bomb that would go undetected through airport security, one counter-terrorism official told the AP news agency.

The counter-terrorism official declined to describe the bomb, but officials in the past have raised concerns about explosives being surgically implanted.

Syrian fighters

American intelligence has picked up indications that bomb makers from al-Qaeda's Yemen affiliate have traveled to Syria to link up with the al-Qaeda affiliate there.

Americans and others have traveled to Syria over the past year to join al-Nusra Front's fight against the Syrian government.

The airports were located in the Middle East and Europe, according to an official at the Department of Homeland Security, AFP news agency reported.

US officials fear that one of the many US or Western European passport holders who have traveled to Syria to fight could carry such a bomb onto an American plane.

Al-Qaeda in the Arabian Peninsula has previously been responsible for plots involving suicide bombers with explosives designed to hide inside underwear and explosives hidden inside printer cartridges shipped on cargo planes.

The Homeland Security Department would not say whether the call for enhanced security was in response to a specific threat.

*Agencies