A complex mosaic of nations, tribes and militants is hampering strategies by African and Western nations to staunch the flow of weapons and fighters south from the civil war in Libya into the Sahara-Sahel region.

Libya's civil war and the end of Muammar Gaddafi's rule has pumped more weapons and men into an already volatile mix of local rebels, cross-border criminals and Islamists in the remote desert regions of Mali, Niger and Mauritania.

Diplomacy and military cooperation has made some progress towards intercepting arms and fighters but much needs to be done.

Heightened fears of trouble in the Sahara-Sahel band range from another round of Tuareg rebellion and the prospect of al Qaeda's local factions securing better weapons to a spike in banditry and smuggling across a range of fragile nations.

Pledges of help from Europe as well as the arrival of military aid from France and the United States ought to dovetail with a spate of meetings between presidents and foreign ministers from the region, including Algeria.

The European Union's aid commissioner Andris Piebalgs on Wednesday promised 62 million euros (53.4 million pounds) in aid to Mali, most aimed at shoring up security in the northern desert.

The ousting of Gaddafi also removes a man responsible for nurturing and funding various rebel movements across the region.

It was in the southern Libyan desert that Gaddafi's son and heir apparent Saif al-Islam was captured, betrayed by the nomad guide hired to spirit him across the border to Niger.

GADDAFI AND THE TUAREGS

Tensions run high in Libya's southern Sahara where many Tuareg nomad tribes, who roam the desert spanning the borders of Libya and its neighbours, backed Gaddafi late into the war which toppled the leader of 42 years.

Many Tuareg, known for the indigo blue-coloured scarves and turbans they wear, backed Gaddafi because he supported their rebellion against the governments of Mali and Niger -- where there are large populations of Tuareg -- in the 1970s and later allowed more than 100,000 to settle in southern Libya.

The tribes are important to regional security because the Tuareg have huge influence in the vast, empty desert expanses which are often exploited by drug traffickers and Islamist militants as a safe haven for their operations.

Porous borders, discontent and availability of arms make this region one of the potential hot spots to present an armed challenge to the interim Libyan government.

But the Tuareg say they are the victims of bad press, named as Gaddafi mercenaries because he used black Africans to fight in the north and accused of giving shelter to Gaddafi's family and his loyalists, a claim that many in the north uphold.

Analysts warn the myriad of local issues and lingering regional distrust make progress slow on the ground.

New resources and shared interests may push Sahelian countries towards tighter cooperation. But talks and money are not the only necessary ingredients in this endeavour, Alex Thurston said in a posting on Sahel Blog.

The challenges each country in the region faces differ, and lingering political tensions and mistrust may continue to limit or slow the development of cooperative frameworks, he added.

COMPETITION FOR FIGHTERS

Analysts say Mali, whose rugged north has long been a safe haven for Islamists, rebels and smugglers, is the weak point in the region. It has been accused of going soft while others, especially Mauritania, sought a military response.

It is here where the return of hundreds of heavily armed Tuareg, who once fought in Gaddafi's ranks, is most felt.

Government delegations have held talks with various Tuareg factions, some of which claim to be forming a new rebellion for an independent Tuareg state in the desert, though no attacks on authorities have taken place.

Traditional authority is now being challenged in both the Arab and Tuareg communities of northern Mali as (al Qaeda), smugglers, rebel leaders and traffickers compete for the loyalty of young men in a severely underdeveloped region, analyst Andrew McGregor said in a report.

If another round of Tuareg rebellion breaks out in Mali, the security forces will be hard pressed to deal with it, leaving ample space and opportunity for AQIM (al Qaeda in the northern Maghreb) to expand its influence and power at the expense of the Malian state.

Mali earlier this year launched a $69 million (44.4 million pounds) plan to develop the north, where tourism has dried up due to security fears, adding to chronic underdevelopment.

Yet, such projects take time and there have been previous efforts to end Tuareg complaints of marginalisation that fuelled rebellions in the 1990s and between 2007-9.

In a sign of deepening ties, the United States handed over $9 million in counter-terrorism kit to Mali's military last month. In June, Bamako's cooperation with Mauritania appeared to improve with joint anti-al Qaeda operations in Mali's western Wagadou forest.

Mali's military chief has called for more joint operations between the two nations. Yet, when Nouakchott hit the same camp of suspected Islamists last month, it did so without informing Bamako, according to security sources in Nouakchott.

Mali's President Amadou Toumani Toure has visited Algeria, another critic of Bamako's soft stance, but some in Mali's media have speculated that Algiers may seek to fill Gaddafi's boots as meddler-in-chief in Tuareg politics and regional security.

DEADLY CARGO

Concerns over Libya's missing weapons escalated throughout the conflict, with the United Nations Security Council last month calling on Libya's new rulers to track the weapons down.

Niger -- a recipient of French support that will get more trucks and helicopters from Paris next year -- has clashed with gunmen apparently trying to ferry weapons from Libya to Mali.

Peter Pham, from the U.S.-based Atlantic Council, called the quality and quantity of weapons coming from Libya a potential game-changer. He said armour-piercing RPG-29s, an upgrade from the more commonly used RPG-7, may have left Libya.

Figures on what has left the country are difficult to come by, though a U.S. official said this month that most of the shoulder-fired anti-aircraft missiles appeared to still be in Libya.

One of al Qaeda's commanders in the Sahara has said the group profited from the Libyan conflict by securing weapons.

But a diplomat who follows regional security issues said there was no evidence al Qaeda had profited on a large scale from either arms or men, so far.

The Tuareg have definitely come out of this better armed ... The criminals may also be getting an upper hand, the diplomat said, underscoring the range of various armed groups operating in the porous region. He asked not to be named.

Long-used for ferrying cigarettes, weapons and people, the Sahara's smuggling routes are now also a path for a far more lucrative commodity - Latin American cocaine headed for Europe -

raising the stakes and risks those involved are ready to take.

A spike in activity by Nigerian Islamist group Boko Haram, coupled by increased reports that it has at least some links to al Qaeda, has added a new dimension to the regional threat.

Whether violence is happening now or battles erupt later, it seems depressingly clear that such large outflows of deadly cargo can only fuel and intensify conflict in the Sahel for some time to come, Andrew Lebovich said on the al-Wasat blog.

(Additional reporting by Tiemoko Diallo in Bamako, Laurent Prieur in Nouakchott and Abdoulaye Massalatchi in Niamey; Editing by Richard Valdmanis and Peter Millership)