French-led troops were advancing on Mali's fabled desert city of Timbuktu on Sunday after capturing a string of other towns in their offensive against Islamist militant groups in the north of the country.

French air strikes destroyed the home of the leader of an Al Qaeda linked group in the town of Kidal overnight, 24 hours after French and Malian troops seized Gao, the biggest victory so far in their 17-day operation against the militants.

French Prime Minister Jean-Marc Ayrault said the troops were advancing on Timbuktu, a desert trading post and center of Islamic learning for centuries, where 333 revered saints are believed to be buried.

Ayrault said the troops were currently "around Gao and (will be) soon near Timbuktu."

Meanwhile, African leaders meeting in the Ethiopian capital were discussing scaling up the number of African troops to join the offensive, after the African Union's outgoing chief admitted the body had not done enough to help Mali.

Gao is the biggest of six towns seized by the French and Malian troops since they launched their offensive on January 11 to wrest the vast desert north from the Islamists, who imposed a particularly brutal version of sharia law in areas under their control.

French-led forces on Saturday took Gao from the Al Qaeda-linked Movement for Oneness and Jihad in West Africa (MUJAO), one of the Islamist groups that have controlled northern Mali for 10 months.

A Malian security source said the home of Ansar Dine (Defenders of the Faith) chief Iyad Ag Ghaly was destroyed in air raids on Islamist bases in Kidal, 1,500 kilometers north of the capital Bamako.

Kidal has been a bastion of Ansar Dine, whose leader is a former soldier and a Tuareg ex-rebel who formed the group last year.

Residents fleeing Timbuktu were jubilant, hailing France for stopping the Islamist juggernaut.

"We have the feeling that we are soon going to be liberated," said Sidi Toure, a 67-year-old trader.

AFP