Al-Qaeda offshoot the Movement for Oneness and Jihad in West Africa (MUJAO) claimed responsibility Friday for a suicide bombing at an army checkpoint in northern Mali, where French-led forces are battling Islamist rebels.

"We claim today's attack against the Malian soldiers who chose the side of the miscreants, the enemies of Islam," MUJAO spokesman Abou Walid Sahraoui told AFP, vowing further attacks.

"Other suicide bombers are on the ground to accomplish Allah's work against miscreants and their accomplices."

The attack in Gao, the largest city in the north, was the first suicide bombing on Malian territory.

An AFP journalist at the site said the bomber was wearing a paramilitary police uniform, and that in addition to an explosives belt he was carrying a larger bomb which did not explode.

The suicide bomber "approached us on a motorbike, he was a Tamashek (Tuareg), and as he came closer he set off his belt," said First Sergeant Mamadou Keita of the Malian army.

"He died immediately and among us, one was injured."

MUJAO, one of a triad of Islamist groups that have been driven from their strongholds by a French-led offensive after occupying northern Mali for 10 months, have vowed to "created a new combat zone" by organising suicide bombings, attacking military convoys and placing landmines.

A landmine blast on Wednesday between the northern towns of Douentza and Gao killed four civilians returning from market, an officer with Mali's paramilitary police said.

That explosion came after a similar blast in the same area on January 31 claimed the lives of two Malian soldiers.

"MUJAO is behind the explosion of two Malian army cars," the group's spokesman Abu Walid Sahraoui said in a text message to AFP.

A month after the French launched a lightning offensive to chase out the Islamists, Paris has warned of "residual jihadist groups" still fighting.