Chadian troops swarmed into the desert town of Kidal in northeastern Mali on Tuesday, securing the last Islamist bastion as global players met in Brussels to carve out a path back to stability for the troubled west African nation.
The French defence ministry said 1,800 Chadian troops had entered Kidal to "secure" the Saharan outpost, after days of air strikes in the surrounding mountains where Islamist insurgents are believed to be hiding in hillside caves near the Algerian border.
"The French are controlling the airport with the back-up of two paratrooper units," a ministry official said, adding that nearly 4,000 French troops were now on the ground in its former colony.
The official said French air strikes had hit 25 targets in recent days, "mainly logistical depots and training centres" in the areas of Aguelhok and Tessalit, near the Algerian border.
French-led forces have driven out the extremist fighters, who had for 10 months controlled a swathe of northern territory the size of Texas, from their key strongholds after sweeping to Mali's aid on January 11.
The rebels slipped away into the Adrar des Ifoghas massif around Kidal, a craggy mountain landscape honeycombed with caves where they are believed to be holding seven French hostages kidnapped in Mali and Niger in 2011 and 2012.
A Tuareg group formerly allied with the Islamists, the Azawad National Liberation Movement (MNLA) -- which was fighting for an independent state but fell out with the extremists who were more interested in imposing sharia -- said it was working with the French against "terrorists" in the region.
"In the framework of anti-terrorist coordination put in place with French forces" the former MNLA rebels will provide intelligence on "top terrorist officials" they have arrested, a spokesman said in Burkina Faso.
The group said it was responsible for the arrest on Sunday of two Islamist leaders, Mohamed Moussa Ag Mohamed, the number three in Ansar Dine (Defenders of the Faith), and Oumeini Ould Baba Akhmed of the Movement for Oneness and Jihad in West Africa (MUJAO).
The MNLA launched a rebellion a year ago fighting for an independent homeland for the desert nomad Tuareg people, who have long felt marginalised by the central government.
But, after being chased out of their strongholds by the Islamists, they have voiced a willingness to negotiate since France launched its intervention. And Mali's interim leadership has welcomed them at the table if they renounce their claim to an independent state.
In France, President Francois Hollande, whose decision to intervene in Mali won him a hero's welcome there during a whirlwind tour on Saturday, defended the decision to send troops in his first address to the European Parliament since taking office.
"There was no time to lose," he said, otherwise "terrorism would have conquered all of Mali".
Hollande also urged Europe to fight drug trafficking in west Africa, saying "terrorism feeds on narcotics trafficking".
Analysts say the groups that seized northern Mali depend on drug trafficking, smuggling and kidnapping to arm themselves.
Western powers have raised concerns the region could become a new breeding ground for terrorists.
On Tuesday three French-Congolese and a Malian were arrested near Paris as part of a probe into a network set up to send jihadists to fight in west Africa.
In Brussels, global players met to carve out plans for Mali's future once the 26-day-old offensive draws to an end.
Mali's Foreign Minister Tieman Coulibaly said as he arrived for the talks that the threat in northern Mali "concerns all civilised countries".
At the top of the immediate political agenda in Brussels will be the dispatch of human rights observers, amid fears of reprisals against light-skinned Tuareg and Arabs who are accused of backing the Islamists.
Aside from rustling up aid and speeding up plans to deploy a formal United Nations peacekeeping force, the delegations from the UN, African Union and other blocs will also mull how to assist Mali hold elections before July 31, restoring constitutional rule after a coup that tipped Mali into chaos on March 22.