International inspectors have to visit hundreds of suspected weapons stockpiles in Libya amid growing fears that huge numbers of shoulder-fired missiles have been looted, a UN envoy said Wednesday.

Ian Martin, head of the UN mission in Libya, also told a Security Council meeting that new previously undeclared sites for storing chemical weapons had been uncovered since the fall of Moamer Kadhafi's government.

World powers have raised fears that militant groups in neighboring countries have obtained Kadhafi's weapons and that the arms could fall into the hands of Al-Qaeda followers.

Kadhafi's regime had "accumulated the largest known stockpile of anti-aircraft missiles," Martin said.

"Thousands were destroyed during NATO operations. But I have to report to you our increasing concerns over the looting and likely proliferation of MANPADS," or Man-Portable Air Defense Systems, Martin told the 15-member Security Council.

He said munitions and large numbers of mines had also been looted.

Nuclear and chemical weapons materials are mainly controlled by National Transitional Council forces.

But Martin noted that "it has become clearer that there are additional sites with previously undeclared chemical weapons or materials that the government is about to formally declare" to international inspectors.

International experts working with the NTC had identified MANPADS sites and storage areas, mainly in eastern Libya, though Martin cautioned that "hundreds" of suspected sites should still be inspected.

He said mines had been laid around many cities and that there were large quantities of unexploded bombs and missiles in Kadhafi's hometown of Sirte and in Bani Walid.

"In Tripoli, many stockpiles are suspected in residential areas, including in schools and hospitals, where they seem to have been moved by Kadhafi forces to conceal them from airstrikes. They mostly remain unsecured," Martin said.

The surface-to-air missiles can be used against civilian jets and other ordnance can easily be converted into car bombs and roadside explosives, according to experts.

Human Rights Watch said Tuesday that two unguarded sites it has inspected near Sirte contained surface-to-air missiles, tank and mortar rounds, large numbers of munitions and thousands of guided and unguided aerial weapons.

The group said that while its representatives were at one sites, which had already been looted, civilians and armed fighters arrived with pickup trucks to remove more weapons.