The U.S. Embassy in Algeria received information about the threat and quickly alerted potential targets, the State Department said in a statement. The warning highlights the urgency of the Obama administration's effort to help Libya's opposition government lock up as many weapons as possible to prevent them from fueling an insurgency or falling into the hands of al-Qaida operating across North Africa.
As an urgent measure, officials told The Associated Press earlier Friday that the administration is sending several additional weapons experts to Libya to help train local units to locate and destroy weapons. The top focus is on the estimated 20,000 shoulder-launched missiles, called MANPADs, which Gadhafi assembled during his four-decade rule. The weapon can be used to shoot down helicopters or civil jetliners.
"My team has no higher priority than addressing this threat," said Andrew Shapiro, the assistant secretary of state for political-military affairs. "We are utilizing every possible tool to reduce the availability of loose missiles from Libya."
The decision to increase weapons-related aid comes after U.S. officials received a request Friday from Libya's National Transitional Council for greater assistance in securing Gadhafi's former stocks of conventional weapons. The deposed Libyan dictator, who is still at large, halted his weapons of mass destruction programs in 2004. U.S. and international officials believe his leftover stocks of chemical and nuclear material are safe - and in a form that cannot be quickly be made into weapons.
But so-called MANPADs pose a serious danger. While many of the aging rockets may not work, the Soviet-era man-portable air defense systems require no special training to operate and officials say prices have fallen on the regional black market, suggesting some of Gadhafi's stores have been sold. The country's new leaders, who are struggling to establish a government, have failed to secure many of the weapons caches. Witnesses have watched looters, former rebel fighters or anyone with a truck carry them away.
Speaking on condition of anonymity to discuss intelligence matters, a U.S. official said the terror threat was related to weapons such as MANPADs may have been obtained by terrorists affiliated with al-Qaida in the Islamic Maghreb, the group's North Africa wing.
The State Department statement said the U.S. and its allies "have put considerable pressure on al-Qaida and have degraded much of the group's abilities, including its capacity to raise money, train recruits and plan attacks." But it warned of the continued terrorist threat from the group and its affiliates. The U.S. didn't say where its intelligence came from, but noted that Algeria's government has long been among the strongest U.S. partners against al-Qaida.
To stem any flow of weapons, the U.S. already has two technical experts in Libya, training the Western-backed rebel authorities in weapons destruction and planning to embed with NTC units that will scour the desert for weapons trafficking. Officials said they will now be augmented by several more contractors, creating several additional Libyan teams.
Speaking on condition of anonymity to discuss confidential plans, the U.S. officials said the teams would initially seek to secure as many remaining sites as possible. That would include the large weapons depots of Gardabiya, east of Sirte, and Jufra, in the center of the country, once rebels wrest control of the sites from forces still loyal to Gadhafi. Later, the teams will proceed more methodically to round up stolen weapons and assess long-term security needs.
Some experts say the administration hasn't moved fast enough.
Fred Abrahams, a special adviser for Human Rights Watch, said groups have been pushing Libyan rebels, the U.S. government and NATO for weeks to do more to fight weapons proliferation. "They all really missed the boat," he told the AP. "We're seeing some progress now but of course so much is already gone."
For depots that already have been looted, Abrahams said that Libyan authorities should work with local brigades to turn in land mines, surface-to-air missiles and other "unnecessary weapons" to a central storehouse that would be easier to monitor - perhaps with U.N. support.
Journalists and human rights groups have discovered huge weapons depots around Tripoli since the former rebels swept into the capital Aug. 21. Many of the sites remain poorly guarded.
But administration officials said the U.S. has been working with rebels since April to coordinate a strategy. A U.S. government arms expert has been working with opposition leaders in the former rebel capital of Benghazi, while the State Department budgeted $3 million to hire two international weapons disposal teams to locate and destroy MANPADs, land mines and other munitions. Due to the civil war, the international teams only operated in the east of the country and U.S. officials concede that they've only destroyed a "handful" of MANPADs. But stocks are probably far reduced from their estimated peak of 20,000 because some were secured by the NTC, destroyed by NATO airstrikes, or stolen by rebels and used incorrectly during the fighting, officials say. NATO forces, continuing to go after the holdout loyalist forces, said they hit several surface-to-air missile systems with airstrikes earlier this week.
Associated Press writer Matthew Lee contributed to this report.