Updated

As Mali attempts to restore stability through elections after armed conflict with Al Qaeda-linked militias, the spotlight has been thrown on the growing threat of Islamist extremism across the vast Sahel region.

French Foreign Minister Laurent Fabius has referred to the lawless, arid hinterland, stretching from Senegal in the west to Somalia in the east, as "Sahelistan" -- the new front in the global fight against terrorism.

Six months after a French-led military intervention drove Al Qaeda in the Islamic Maghreb (AQIM) and its allies out of the towns they occupied across Mali's desert north there is little information on their fate.

Analysts agree however that Islamists hardened by years of survival under oppressive regimes have been revived across the Sahel, an ungovernable expanse of rock and sand larger than Europe.

After the Arab Spring and the uprising in Libya which toppled dictator Moamer Kadhafi nearly three year ago, many hoped that terrorism in the region could finally be drawing to a close.

But experts have voiced concerns that the tactics of AQIM will grow more sophisticated and violent, following a similar evolution seen in the Nigerian jihadist sect Boko Haram.

"Every state in this region is vulnerable to AQIM, which has been massively bolstered by weapons flow, porous borders and security vacuums in the Sahel, in combination with fragile regional governments," Rudolph Atallah, of the US-based Ansari Africa Center, told the US House of Representatives Committee on Foreign Affairs in May.

Atallah said militant movements such as AQIM, Ansar Dine and The Movement for Oneness and Jihad in West Africa (MUJAO) were capitalising on the discontent of marginalised groups coerced into harsh border areas marked by weak governance, poverty and ethnic tensions.

Since February, Mali has experienced suicide attacks in Timbuktu, Gao and Kidal, all areas briefly under Islamist control after the Tuareg National Movement for the Liberation of Azawad (MNLA) was elbowed out of the north last year by AQIM and its allies.

"We have information according to which some terrorists active in Mali consider Libya as a refuge and a place to reorganise," Francisco Caetano Jose Madeira, the African Union's anti-terrorism chief, told a conference in Algeria last month.

The European Union has offered to cooperate with Libya on tightening border security but Western sources say the lack of organisation since Kadhafi's overthrow makes such a project "very difficult".

The prevailing narrative is that AQIM, which traces its roots back to the Algerian civil war in the early 1990s, suffered a strategic defeat when it melted away in the face of advancing French troops in Mali.

But some analysts have characterised its retreat in January as a tactical withdrawal into the desert and into southern Libya, Algeria, Sudan and Mauritania for the purposes of reorganising.

Islamist fighters thought to belong to Ansar Dine turned up in Sudan's Darfur region bordering Libya and Chad in February, a regional political analyst told AFP.

The authorities have been unable to say how exactly how many Islamists fled to the region but a commander in the rebel Sudan Liberation Army put the number at "hundreds".

Niger, a mainly Muslim former French colony of 17 million people, emerged as one of the Sahel nations most susceptible to Islamist infiltration in the wake of two suicide bombings in May claimed in part by MUJAO in which 20 people died.

Faced with this Islamist threat, the regime of President Mahamadou Issoufou has beefed up security, seriously depleting resources for non-military development in one of the world's poorest countries.

"Since 2011 we have not stopped (increasing) the capabilities of our military," Defence Minister Mahamadou Karidjo said earlier this month.

"Special anti-terrorism forces were formed as well as rapid intervention and monitoring units to prevent attacks," he added. "In terms of deployed forces, you have to see it in terms of a few thousand men positioned at checkpoints into Algeria, and especially mobile patrols along the border with Libya, Mali and Algeria working with the French and American intelligence," a security source based in northern Niger told AFP.

"But our borders are porous and so immense that there will always be gaps through which to infiltrate our territory," the official admitted.

Chad, so far immune to the Islamist threat from the Mali conflict despite deploying troops to fight alongside the French, put its success down to border security tightened during the Libyan conflict.

"Air and land surveillance of our territory goes on night and day. The Lake Chad zone on the Nigerian border is monitored by a multinational force composed of the river countries," a security source said.

"A joint Chad-Sudan force that keeps an eye on the east. Our defence forces control the northern and western border with Niger. The country has made arrangements for all contingencies."