Northrop Grumman chief executive Ronald Sugar told AFP "some airlines" had expressed interest in using an adapted version of a system normally used in warplanes.

Shoulder-fired missiles are increasingly available on the black market and could be used by terrorists to cripple commercial aviation, analysts have said.

"We are talking to some of them (airlines) and conducting feasibility assessments," said Sugar, who is in Singapore to attend this year's edition of the 2004 Asian Aerospace conference and exhibition which kicks off Tuesday.

He said it would probably take a few years to get all wide-bodied planes equipped with anti-missile technology.

Last week, Singapore Coordinating Minister for Security and Defence Tony Tan said the defence ministry was looking into developing such a system.

Tan, who is also one of two deputy prime ministers, said it may take at least a year before planes with flag carrier Singapore Airlines and its regional subsidiary, SilkAir, can be equipped with anti-missile defence systems.

The vulnerability of commercial aircraft was highlighted in November last year when a DHL cargo jet was hit by what was believed to be a shoulder-fired missile near Baghdad International Airport in Iraq.

In November 2002, a missile was fired at an Israeli charter aircraft in Mombasa, Kenya, but missed.

WAR.WIRE