UNITED NATIONS, March 11 (Reuters) - Shoulder-launched anti-aircraft missiles have been trafficked out of Libya to Chad, Mali, Tunisia, Lebanon and likely Central African Republic, with attempts made to send them to Syrian opposition groups, according to a U.N. report on Tuesday.

An independent panel of experts monitoring U.N. sanctions on Libya, that include an arms embargo imposed at the start of the 2011 uprising that ousted leader Muammar Gaddafi, reported that the weapons, known as MANPADs, that were found in Mali and Tunisia “were clearly part of terrorist groups’ arsenals.”

“Despite efforts by Libya and other countries to account for and secure MANPADs in Libya, Panel sources state that thousands of MANPADs were still available in arsenals controlled by a wide array of non-state actors with tenuous or non-existent links to Libyan national authorities,” the experts said in their final report to the U.N. Security Council.

“To date the Panel has documented transfers of Libyan MANPADs and other short range surface to air missiles in ... Chad, Mali, Tunisia, Lebanon and potentially Central African Republic (the latter case still being under investigation),” the experts said.

The fragile Libyan government is struggling to rein in militias that helped oust Gaddafi and now defy state authority. It has little control over its borders and while trying to rebuild its army, analysts say it is not yet a match for battle-hardened militias who ousted Gaddafi in eight-months.

“Over the past three years, Libya has become a primary source of illicit weapons,” according to the U.N. report.

The U.N. experts said Libya has been a key source of arms for Syria opposition groups due to “popular sympathies for the Syrian opposition, large available stockpiles of weapons, the lack of law enforcement and a new generation of domestic arms dealers who appeared during the Libyan uprising.”

“Sources indicated to the Panel that the Syrian Arab Republic is also becoming a source of onward proliferation itself, including to Iraq and Lebanon,” according to the report, which covers the past year.

The panel said that weapons found aboard a ship, the Letfallah II, when it was seized by Lebanese authorities in 2012 “proved there had been attempts to transfer MANPADs to the Syrian opposition from Libya.”

FACEBOOK TRADE

Under the arms embargo the Libyan government must notify the U.N. Security Council Libya sanctions committee of any weapons purchases it intends to make.

“The Panel has reason to believe that some transfers of arms and ammunition have taken place since the end of the revolution in violation of the arms embargo,” the experts said. “Those transfers undermine the effort of the Libyan authorities to build an accountable and transparent procurement process.”

Libya’s U.N. envoy Ibrahim Dabbashi said on Monday that “any request for approval for exporting weapons to Libya that is not done via the Libyan mission at the U.N. or with the knowledge of this mission would be considered a request from a party that does not belong to the Libyan government.”

A year ago the U.N. Security Council made it easier for Libya to obtain non-lethal equipment such as bulletproof vests and armored cars but expressed concern at the spread of weapons from the country to nearby states.

The U.N. experts expressed concern about arms flowing into the civilian market in Libya in violation of the arm embargo. The report found that a number of shops openly sell small arms and that weapons on display were brand new.

“Retailers explained that most of the materiel was procured for Turkey because of low prices,” said the experts, adding that Turkey was investigating the claims. “New guns are also advertised on Facebook pages dedicated to trade between private individuals.”

Facebook Inc and its photo sharing subsidiary, Instagram, announced last week that they will delete posts offering to buy or sell guns without background checks.

“Handguns and related ammunition are still the weapon of choice,” according to the report. “Importing such materiel is therefore a lucrative business and seizures bound for Libya made in 2013 clearly reflect that trend.”

The full Panel of Experts report can be seen here: www.un.org/ga/search/view_doc.asp?symbol=S/2014/106