Tuareg rebels in northern Mali have captured two senior Islamist insurgents fleeing French airstrikes toward the Algerian border, as France pressed ahead with its bombing campaign against al Qaeda's Saharan desert camps.

Pro-autonomy Tuareg MNLA rebels said yesterday they had seized Mohamed Moussa Ag Mohamed, an Islamist leader who imposed sharia law in the desert town of Timbuktu, and Oumeini Ould Baba Akhmed, believed to be responsible for the kidnapping of a French hostage by the al Qaeda splinter group MUJWA.

"We chased an Islamist convoy close to the frontier and arrested the two men the day before yesterday," Ibrahim Ag Assaleh, spokesman for the MNLA, said from Ouagadougou in Burkina Faso. "They have been questioned and sent to Kidal."

France has deployed 3500 ground troops, warplanes and armoured vehicles in its three-week-old Operation Serval in Mali, which has broken the Islamists' 10-month grip on northern towns.

Paris and its international partners want to prevent the Islamists from using Mali's vast northern desert as a base to launch attacks on neighbour- ing African countries and the West.