Moamer Kadhafi's arms stockpiles could remain a threat long after his death, as some are feared to have been sent to Darfur rebels, Al-Qaeda in North Africa and other militants further afield.

There is "very serious concern" that weapons, ranging from shoulder-fired missiles to machine guns and ammunition, may have crossed Libya's borders into neighboring countries, UN envoy to Libya Ian Martin said.

Assault rifles, rocket-propelled grenades and machine guns were all taken from Kadhafi armories and supply depots by the rebels who ousted him. Much has already passed across Libya's porous borders, diplomats and experts say.

One western intelligence report has spoken of truckloads of guns passing through Sudan's war-stricken Darfur region en route to groups in the restive South Kordofan and Blue Nile states.

"We cannot exclude the possibility that some weapons have crossed into Darfur from Libya," Daffa-Alla Elhag Ali Osman, Sudan's UN envoy, told AFP.

Other African states have expressed similar concerns.

"What is sure is that the arms have gone into Chad, Mali and Niger," Mauritania's Foreign Minister Hamadi Ould Hamadi told AFP at the UN headquarters in New York.

Niger's President Mahamadou Issoufou held talks with the Libyan National Transitional Council (NTC) leaders about the arms on the sidelines of the UN General Assembly last month.

Issoufou said the weapons are "spread across the Sahel-Sahara region and could fall into the hands of terrorists."

Kadhafi's son Saadi, three generals and a former security services chief are among 32 associates of the slain dictator who have taken refuge in Niger.

Military chiefs and diplomats from Algeria, Mauritania, Morocco, Tunisia and European nations France, Italy, Malta, Portugal and Spain held their own recent meeting on the arms, a diplomatic source told AFP.

The talks focused on how Al-Qaeda in the Islamic Maghreb (AQIM) could get the Libya arms. European governments are worried that the machine guns and missiles could be used on their own territory.

The weapons, particularly shoulder-fired surface-to-air missiles capable of bringing down aircraft, are a key concern of the UN mission in Libya.

"We are doing our best to facilitate the securing of chemical weapons stocks, of nuclear material, of MANPADs and of other ammunition," Martin said, using the military term for the missiles.

"Although the chemical weapons and nuclear material appear to be secure, there is very serious concern that a lot of other weaponry has gone missing and may have already crossed borders. So we are trying to assist efforts to address that within Libya," the UN envoy added.

Britain has expressed concern about reports of weapons entering Sudan, and the United States is working with Libya's interim leaders to secure the stockpiles.

"Since the beginning of the crisis, we have been actively engaged with our allies and partners to support Libya's effort to secure all conventional weapons stockpiles including recovery, control and disposal of shoulder-fired anti-aircraft missiles," White House spokesman Jay Carney said recently.

US contractor specialists are working with the new Libyan leadership to secure weapons stockpiles, he added.

But there are estimates that Kadhafi's forces had up to 20,000 MANPAD missiles.

"The fallout from these stockpiles could last for years in Africa," said one African diplomat, speaking on condition of anonymity while attending disarmament talks at the United Nations.

"There are far fewer arms in Somalia, but the Islamists are already supplying groups in Yemen, Ethiopia and countries in the region. All around Libya there are groups who will take advantage of Kadhafi's downfall."