PARIS: The French intervention force in Mali has wrapped up most of its work but there are still some problem areas in the north, Defence Minister Jean-Yves Le Drian said Friday.

Some 4,000 French troops are in Mali working with West African forces and Malian soldiers to hunt down Islamist rebels after a Paris-led offensive launched in January drove them from areas of northern Mali they seized last year.

"We have accomplished a large part of the work... It's not completely finished, there are still two pockets (of resistance)," Le Drian said on Europe 1 radio.

He said the other challenge was to secure the region around the main northern city of Gao, adding that the French troops were "practically in face-to-face combat" with the Islamists.

Le Drian said fighters from Al-Qaeda in the Islamic Maghreb (AQIM) were still sneaking in from the mountainous fareastern north.

"As we speak, there are more interventions in the mountains and there are patrols chasing them," he said.

The minister, speaking from the Mali capital Bamako, said two French Islamist fighters had been arrested.

"This shows that... there is a terrorist network in place to recruit fighters which takes in radical youths, like those who have fought in Afghanistan and Syria," he said.