By John Irish
PARIS (Reuters) - France is setting up a base in northern Niger as part of an operation aimed at stopping al Qaeda-linked militants from crossing the Sahel-Sahara region between southern Libya to Mauritania, officials said.
Paris, which has led efforts to push back Islamists in the region since intervening in its former colony Mali last year, redeployed troops across West Africa earlier this year to form a counter-terrorism force.
Under the new plan, about 3,000 French troops are now operating out of Mali, Burkina Faso, Niger and Chad -- countries straddling the vast arid Sahel band -- with the aim of stamping out Islamist fighters across the region. Another 1,000 soldiers are providing logistical support in Gabon and Senegal.
"A base is being set up in northern Niger with the throbbing headache of Libya in mind," a French diplomat said.
French officials have repeated for several months they are concerned by events in Libya, warning that the political void in the north is creating favorable conditions for Islamist groups to regroup in the barren south of the country.
Diplomatic sources estimate about 300 fighters linked to al Qaeda's North African arm AQIM, including a splinter group formed by veteran Islamist commander Mokhtar Belmokhtar, are operating in southern Libya, the start of smuggling and trafficking routes across the region.
Three years after they launched air strikes to help topple Muammar Gaddafi, Western powers including France have ruled out military intervention in Libya, fearing that it could further destabilize the situation given that countries across the region are backing different political and armed groups in Libya.
However, with France particularly exposed in the Sahel-Sahara region and its forces now engaged in a support role against Islamic State militants in Iraq, Paris is stepping up efforts to squeeze militants in the area.
The murder of a French citizen last week in neighboring Algeria by former AQIM militants who pledged allegiance to Islamic State also appears to have toughened Paris' resolve.
"The approach to (fighting terrorism) is global," Army spokesman Gilles Jaron said on Thursday. "We are on the front line in the Sahel-Sahara region and supporting in Iraq."
The French operation, dubbed Barkhane after the name of a kind of sand dune formed by desert winds, has set up its headquarters in the Chadian capital N'Djamena, but also placed an outpost in northern Chad about 200 kilometers from the Libyan border.
Jaron said that in Niger, where French and American drones are already operating, the base was still being finalised, but would have capacity for as many as 200 soldiers with aerial support.
"The aim is to bring together areas that interest us. The transit points which terrorists are likely to use," he said.
There have been some notable successes in recent weeks. Two diplomatic sources said Abou Aassim El-Mouhajir, a spokesman for Belmokhtar's "Those Who Sign in Blood" brigade, was captured by French troops in August.
French media said he had been taken in Niger.
Jaron said four suspected militants were also captured on Sept. 24 near Gao in northern Mali, where France handed the bulk of the security control to the U.N. MINUSMA peacekeeping forces.
At the same time there has been an increase in attacks on foreign troops in Mali, including the death of 10 Chadian soldiers in September.
The U.N.'s peacekeeping chief Herve Ladsous said last week that with many French troops leaving the north of Mali, U.N. forces were being targeted and finding it difficult to respond due to a lack of helicopters and special forces.
"It's a problem that is being resolved. We want the MINUSMA to be up to scratch so we can focus on our number one job: getting rid of AQIM," said a French defense ministry source.
(Editing by Dominic Evans)