News weekly Der Spiegel reported on its website that Admiral Giampaolo di Paola, who chairs the committee of NATO military chiefs, held a secret briefing for German MPs on Monday, in which he expressed the alliance's concerns.

The weapons could end up in other countries and in the wrong hands, the admiral said, according to Spiegel, "anywhere from Kenya to Kunduz" in Afghanistan.

The missiles present "a serious threat to civil aviation," the Italian admiral reportedly said.

The reported comments echoed remarks made by a military official of Libya's new leadership on Saturday.

General Mohammed Adia, in charge of armaments at the defence ministry, told reporters that "about 5,000" SAM-7 anti-aircraft rockets were missing.

"Unfortunately, some of these missiles could have fallen into the wrong hands ... abroad" the general told reporters at a former arms depot of ousted Libyan strongman Moamer Qadhafi in Benghazi.

The United States has said it is working closely with Libya's new interim leaders to secure arms stockpiles, amid concerns over weapons proliferation.

The US State Department has provided $3 million to help destroy weapons.