Brian Roehrkasse, a spokesman with the Department of Homeland Security, said US officials have been sent to help improve security in Basra and Baghdad in Iraq, as well as in a number of Asian and European airports, which he declined to specify for security reasons.

Investigators from the federal Transportation Security Adminstration, are working with the Federal Bureau of Investigation, the Department of State and other US agencies in the effort to help improve on-ground security at the airports, he said.

"We are going to countries that want to work with us," Roehrkasse said.

"They are airports that have US-flagged aircraft flying in and out of them."

Similar efforts to improve airport security from portable missile attacks are already underway at US airports, Roehrkasse said.

The move is part of the federal goverment's response to recent intelligence reports suggesting that a terrorist attack using small heat-seeking missiles may be imminent.

Roehrkasse said that while "the US intelligence community does not have any specific intelligence that al-Qaeda intends to use these weapons for a major attack against US commercial aviation," officials felt concerned about a growing possibility of such an attack.

The best-known portable missiles are the American-made Stinger and the Russian-made SA-7.

Aviation officials have said the missiles, which can be bought on the black market for as little as 5,000 dollars apiece, can reach commercial aircraft from as far as 30 miles (50 kilometers) from an airport and can reach altitudes of about 10,000 feet (3000 meters) for older systems and 18,000 feet (5500 meters) feet for newer weapons.

A US congressional report earlier this year determined that the worldwide inventory of portable surface-to-air missiles probably exceeds 500,000 and may be as high as 700,000.

US lawmaker John Mica, chairman of the House of Representatives' Aviation Subcommittee, which issued the report, has introduced legislation calling for outfitting all of the nearly 7,000 US commercial aircraft with anti-missile technology -- at a cost of as much as two million dollars per plane.

Mica advocates retrofitting existing aircraft with decoy flares, infrared jamming devices, or high-powered lasers -- all of which could deter an incoming missile.

A spokesman for the Florida lawmaker said Thursday that while Mica welcomes US moves to improve security at foreign airports where American aircraft are likely to land, he is still convinced of the need to equip commercial airliners with their own defenses.

"There are too many stinger and shoulder-launched (weapons) for inspectors to be able to catch all of them," said spokesman Gary Burns.

WAR.WIRE