On the first leg of a three-stop visit to West Africa, French Defence Minister Jean-Yves Le Drian said that the Ivory Coast will become the main centre of his country's "fight against terrorism" in the Sahel.

Pockets of al Qaeda-linked fighters are still holding out across the north of Mali, more than a year after the French offensive aimed at driving them from the desert region they occupied for most of 2012 after hijacking a rebellion by Tuareg separatists.

After being scattered across Mali and into neighbouring countries, they have now regrouped and stepped up operations in recent months, Le Drian said on Friday, the Reuters news agency reported.

"We have decided to reorganise our military presence in the entire region with the primary aim to better facilitate the fight against terrorism," Le Drian told a news conference in Abidjan after meeting with Ivorian President Alassane Ouattara.

France is particularly worried by the situation in Libya where more than two-and-a-half years after the fall of former leader Muammar Gaddafi, the oil-rich North African state is struggling to contain violence between rival forces, and al Qaeda-linked fighters are gaining ground in the south.

French defence officials say the new phase in operations will allow their forces to operate freely across borders to strike the armed groups.

It was recently approved by the main countries concerned - Mauritania, Mali, Niger, Chad and Burkina Faso.

Regional centres

French forces will now be based in four regional centres. Some will be in Gao in northern Mali, others in Niger's capital Niamey, where French surveillance drones are based, and in the Burkina Faso capital Ouagadougou, where until now special forces have launched raids into the desert.

The fourth centre will be in the Chadian capital N'Djamena, where the operations will be co-ordinated.

Smaller bases to launch strikes are also being set up with Abidjan in the Ivory Coast as the mission's logistical hub.

"As I've said before we have decided to transform our Licorne presence at the base in Abidjan in an advance operational base which will take effect from the 1st of January next year," Le Drian said.

"This will mean the reinforcement of our perennial force here and of our presence here for the continuity of our quality relationship in the military domain."

The minister said 1,000 soldiers would remain in Mali and 3,000 in the Sahel-Sahara zone, and that the force would be there "for as long as necessary".