"Their illicit proliferation to terrorists and non-state actors is a significant threat to global civil aviation and international peacekeeping efforts," Australian ambassador Caroline Millar told the international Conference on Disarmament.

Millar underlined that recent arrests in Switzerland showed that the proliferation of the missiles, known as "Man Portable Air Defence Systems" (MANPADS), "is not an idle threat".

In June, Swiss justice authorities revealed that they had thwarted a plot by a group of North Africans to attack an Israeli El Al airliner. Seven people were arrested.

Media reports said the group were planning to use a shoulder-launched missile near a Swiss airport.

France called on the forum to take up the issue urgently.

"The issue of the use of MANPADS against civilian airliners is, without any doubt whatsoever, a serious source of concern at the moment," said French disarmament ambassador Francois Rivasseau.

In 2003, 33 nations agreed on a series of measures to control exports and storage of portable anti-aircraft missiles. The initiative was backed by the G8 summit. Since then Australia has sought to promote controls in Asia.

But diplomats said there was still a need for additional measures to counter the threat.

"As long as there is leakage from existing stockpiles and diversion from the legitimate trade in these arms, terrorists will continue to acquire and use them," said British disarmament representative Fiona Paterson.

Australia has argued that there is a need to ensure that the missiles are only transferred to states.

The 66-nation permanent Conference on Disarmament, which is hosted by the United Nations, is the world's main forum for arms control treaties.

About 42 civilian airliners have been hit by portable missiles since the 1970s and 29 of them crashed, according to the International Civil Aviation Organisation.

In 1973, the first known attempt to use a shoulder-launched missile, against an El Al airliner, was foiled at Rome airport.

Two years later, a Yugoslav airliner was mistakenly hit on the ground at Orly airport in Paris during an attack on an Israeli plane.

Two missiles missed another Israeli airliner shortly after it took off from Mombasa airport in Kenya in 2002.

The Geneva-based Small Arms Survey, which monitors weapons transfers, estimated in 2004 that 105 nations had them in their arsenals, along with at least 13 rebel or terror groups.

Fears about proliferation were heightened after the United States covertly supplied Stinger missiles to Afghan groups fighting against the Soviet occupation of Afghanistan in the 1980s.

Afterwards, many surplus Stingers are thought to have stayed in the hands of Afghan groups or found their way onto the black market alongside similar but less sophisticated Russian weapons.

More are thought to have seeped into the wrong hands in Iraq, where the Small Arms Survey estimated that at least 1,500 were "at large" following the collapse of Saddam Hussein's regime.

Groups that have the weapons are thought to include Hezbollah in Lebanon, Colombia's FARC rebels, and Sri Lanka's Tamil Tigers, according to the Small Arms Survey.

Although older models require a high degree of training to operate effectively, newer generation MANPADS with a range of up to six kilometres (four miles) are said to be much easier to use.

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