There is a risk of "terrorist" groups setting up in the deserts of northern Mali, French President Francois Hollande warned Monday after talks with Niger's President Mahamadou Issoufou in Paris.

"There is a threat of terrorist groups setting up in northern Mali. There is outside intervention that is destabilising Mali and setting up groups whose vocation goes well beyond Mali, in Africa and perhaps beyond," Hollande said.

Issoufou, whose country shares a long and porous desert border with Mali, warned last week that jihadi fighters from Afghanistan and Pakistan were training Islamist groups there as world powers mull armed intervention.

Mali, once considered a beacon of democracy in western Africa, has plunged into chaos since the collapse of Moamer Kadhafi's regime in Libya last year scattered mercenaries and weapons across the Sahel.

Tuareg rebels rekindled their decades-old struggle for independence in January and conquered the entire northern half of Mali virtually unopposed in March, after renegade soldiers who accused then-president Amadou Toumani Toure of failing to do enough to fight the rebellion toppled his regime.

The Tuareg rebels fought alongside a previously unknown Islamist group called Ansar Dine (Defenders of Faith), which is believed to be backed by Al-Qaeda's north African branch.

Al-Qaeda in the Islamic Maghreb (AQIM) has been active for years in northern Mali, where it has launched attacks against government army positions, kidnapped foreigners and allegedly benefitted from drug running.

Government troops have no control over Mali's north, a territory larger than France, heightening fears in the region and beyond that the landlocked country could become a new global haven for Al-Qaeda.