France said Sunday its military offensive that freed northern Mali from the grip of Islamists would be replaced by an operation spanning the wider, largely lawless Sahel region to combat extremist violence.

The so-called Serval offensive kicked off in January last year when French troops came to the help of Malian soldiers to stop Al-Qaeda-linked militants and Tuareg rebels from descending south of its former colony and advancing on the capital Bamako.

President Francois Hollande, speaking on the eve of France's Bastille Day military parade in Paris, said the mission had been "perfectly accomplished".

"As Serval wraps up, Mali is no longer a sanctuary for terrorist groups," he said.

France -- which currently has 1,700 soldiers in Mali -- had initially planned to end Serval in May and redeploy troops to the Sahel region, but fresh clashes between rebels and the army in the flashpoint northern town of Kidal forced Paris to delay the pullout.

The French-led Serval operation, which saw eight soldiers die in 18 months, has largely been deemed a success by the international community.

But French lawmakers warned last week that all was not over in Mali, pointing to ongoing tensions and challenges in passing the baton to another force while a planned UN stabilisation operation in the country is only being slowly deployed.

- 'Our security' at stake -

Defence Minister Jean-Yves Le Drian said Sunday that concern had now shifted to Africa's vast Sahel region along the southern rim of the Sahara desert, whose stability is threatened by Islamist violence.

The new operation there would "make sure there is no upsurge (in terrorism) as there are still major risks that jihadists will develop in the zone stretching from the Horn of Africa to Guinea-Bissau," Le Drian said in a televised interview.

The new "counter-terrorism" operation, codenamed Barkhan, will kick off in the coming days and is being implemented in partnership with five countries -- Mauritania, Mali, Burkina Faso, Niger and Chad -- Le Drian said.

He added that some 3,000 French soldiers would be part of the operation, 1,000 of whom would stay in northern Mali and the rest would be deployed in the other countries.

Drones, helicopters, fighter jets, armoured vehicles and transport planes will also take part in Operation Barkhan -- the name of a crescent-shaped sand dune in the desert -- which will have its headquarters in the Chadian capital N'Djamena.

"The aim is to prevent what I call the highway of all forms of traffic to become a place of permanent passage, where jihadist groups between Libya and the Atlantic Ocean can rebuild themselves, which would lead to serious consequences for our security," Le Drian said.

"It's our security which is at stake."

France is also on the ground in the Central African Republic, which has been hit by more than a year of unrest as mainly Muslim former rebels and predominantly Christian vigilantes engage in deadly tit-for-tat violence.

But despite the presence of thousands of troops -- 2,000 of whom are French -- tensions remain high and ethnic and religious bloodshed that has claimed thousands of lives shows no sign of abating.