Rebels were driven from landmarks in the city of Gao in deadly clashes Thursday, Paris said, as French-backed forces battled to secure Mali's volatile north against Islamist fighters.

At least two civilians were meanwhile wounded after a vehicle exploded near a camp occupied by French and Chadian troops in the city of Kidal, in the conflict's first apparent car bombing, local officials said.

French-led forces are increasingly facing guerrilla-style tactics after their offensive, launched in January, met little resistance to drive the Islamists from the main northern towns of Gao, Kidal and Timbuktu.

A military source said battles erupted overnight Wednesday in Gao after about 40 Islamists infiltrated the city from nearby villages.

The main courthouse was in flames. An AFP correspondent said the fighting was focused near the courthouse and Gao's city hall.

But French Defence Minister Jean-Yves Le Drian, speaking in Brussels, said late Thursday that French-backed Malian forces finally repelled them.

"The rebels occupied the Gao city hall and the governor's residence. Mali army troops, backed up by French forces, reacted and five Islamists were killed. The situation has returned to normal," Le Drian said.

One of Mali's main Islamist groups, the Movement for Oneness and Jihad in West Africa (MUJAO), said it had sent the rebels to Gao and vowed to recapture the city.

"Our fighters entered Gao on Wednesday," MUJAO spokesman Abu Walid Sahraoui told AFP. "Our troops have been ordered to attack. If the enemy is stronger, we'll pull back only to return stronger, until we liberate Gao."

Gao, the main city in Mali's north and 1,200 kilometres (745 miles) from the capital Bamako, was retaken by French and Malian forces on January 26 during an intervention to dislodge rebels who had seized control of the vast desert north last year.

The apparent first car bombing in the conflict occurred just 500 metres (yards) from the camp occupied by French and Chadian forces.

An official in the Kidal governor's office said that the vehicle, apparently driven by a suicide bomber, was targeting the camp but exploded before it could reach the base, killing the driver.

Malian, French and West African troops are working to secure Mali's north against bombings and attacks after a French intervention launched last month dislodged rebels who had seized control of the vast desert area last year.

Mali's Prime Minister Diango Cissoko said this week that large-scale military operations in the north were winding down, but sporadic fighting has continued, with a French legionnaire killed on Tuesday in the mountainous Ifoghas region.

France's army spokesman Thierry Burkhard said that the "Panthere 4" operation in the Ifoghas had already left 30 Islamists dead since the start of the week.

It was unclear who was behind the attack in Kidal, but local Tuareg forces had warned against the deployment of Malian or West African forces in the city, one of their traditional power bases.

Ethnic Tuaregs in northern Mali, who have long sought greater autonomy, initially backed the rebellion but later fell out with the Islamists and had retaken control of Kidal before the arrival of French troops.

About 1,800 Chadian troops were then deployed in the city as part of the West African AFISMA mission that France hopes will eventually become a UN stabilisation force.

Asked whether it was coordinating its efforts with the main Tuareg rebel group, the MNLA, the French military said Thursday it was working with groups that shared its interests.

"It is not a question of collaboration. It's that the French army is pursuing goals that have been clearly identified. The French army of course coordinates with groups that have the same goals as us," military spokesman Colonel Thierry Burkhard told reporters.

Malian forces have been accused of carrying out abuses during their operations in the north, including summary killings, and on Thursday Human Rights Watch urged the government to punish those responsible.

"The Malian government should urgently investigate and prosecute soldiers responsible for torture, summary executions, and enforced disappearances of suspected Islamist rebels and alleged collaborators," the New York-based group said in a statement.