Islamists in Mali have retaken control of a northern town, disarming without a fight a local militia operating there with the aim of wresting back control of the rebel-held north, fighters on both sides said on Sunday.

The fall of Douentza, at one stage occupied by Islamists but for weeks the northernmost town under southern control, illustrates the challenges Mali's government and countries in the region face in securing a deal with or defeating Islamists, including al Qaeda fighters, occupying the desert north.

Oumar Ould Hamaha, a senior Islamist speaking on behalf of the MUJWA group whose men are now in Douentza, 800 km (500 miles) northeast of Bamako, said they took control of the town after fighters of the Ganda Izo militia missed a deadline to disarm.

"Our men came to disarm all those who are armed ... our aim is not to go as far as Bamako," he said.

Ibrahim Maiga, a Ganda Izo leader, confirmed his men had been overpowered without a fight and blamed the rout on a defection in their ranks.

Mali's army is still in tatters after it lost ground to Islamist and secular rebels in fighting earlier this year and the hierarchy then crumbled when disgruntled soldiers ousted the country's president in a March coup.

The officers said they removed President Amadou Toumani Toure partly over his handling of the northern rebellion. But since they came to power they have been accused of meddling in politics rather than preparing a counterattack.

West Africa's regional bloc ECOWAS also wants to deploy troops to Mali but planning has dragged on for months due to the lack of funds and disagreement over what the mission should be.

As a result, local hopes have been pinned on ragtag local militia like the Ganda Izo who have been recruiting and training local youth but lack weapons and basic equipment.