TIMBUKTU, Mali -- In a new phase of the Mali conflict, French airstrikes targeted the fuel depots and desert hideouts of Islamic extremists in northern Mali overnight Monday, as French forces planned to hand control of Timbuktu to the Malian army this week.

After taking control of the key cities of northern Mali, forcing the Islamic rebels to retreat into the desert, the French military intervention is turning away from the cities and targeting the fighters' remote outposts to prevent them from being used as Saharan launch pads for international terrorism.

The French plan to leave the city of Timbuktu on Thursday, Feb. 7, a spokeswoman for the armed forces in the city said Monday. French soldiers took the city last week after Islamic extremists withdrew. Now the French military said it intends to move out of Timbuktu in order to push farther northeast to the strategic city of Gao.

"The 600 soldiers currently based in Timbuktu will be heading toward Gao in order to pursue their mission," said Capt. Nadia, the spokeswoman, who only provided her first name in keeping with French military protocol. She said that the force in Timbuktu will be replaced by a small contingent of French soldiers, though she declined to say when they would arrive.

On Monday, French troops in armoured personnel carriers were still patrolling Timbuktu. In the city's military camps, newly arrived Malian troops were cleaning their weapons Monday and holding meetings to prepare to take over the security of the city once the French leave.

There are signs that the Islamic rebels are beginning a guerrilla-type of conflict from their desert retreats as land mine explosions have killed four Malian soldiers and two civilians throughout the northern region in recent days.

The two civilians died in an explosion from a land mine, or an improvised explosive device, on the road in northeastern Mali that links Kidal, Anefis and North Darane, the United Nations Office for the Coordination of Humanitarian Affairs said in a statement Monday.

Four soldiers were killed last week by a land mine explosion in the northeast area near Gossi. The French reported that two other land mines have been found in that vicinity, and early Monday they detonated one of the mines.

French airstrikes targeted the Islamic extremists' desert bases and fuel depots in northern Mali overnight.

French Foreign Minister Laurent Fabius said on France-Inter radio Monday that the strikes hit the Kidal region, near the border with Algeria, for the second night in a row. The extremists "cannot stay there a long time unless they have ways to get new supplies," he said.

French Mirage and Rafale planes also pounded extremist training camps as well as arms and fuel depots from Saturday night into the early hours of Sunday, north of the town of Kidal and in the Tessalit region. France's Defence Ministry said Monday night that 25 depots and training centres had been targeted by fighter jets and attack helicopters.

The French intervened in Mali on Jan. 11 to stem the advance of the al-Qaida-linked fighters, who had taken over the country's north, enforced harsh rules on the population and plotted a terrorist attack in neighbouring Algeria. The French troops arrived when the Islamic extremists threatened to move farther south.

After pushing extremists out of key northern cities, France is now pushing to hand over control of those sites to African forces from a United Nations-authorized force made up of thousands of troops from nearby countries.

"In the cities that we are holding we want to be quickly replaced by the African forces," Fabius said Monday.

Asked whether the French could pull out of the fabled city of Timbuktu and hand it to African forces as soon as Tuesday, Fabius responded, "Yes, it could happen very fast. We are working on it because our vocation is not to stay in the long term."

But it is far from clear that the African forces -- much less the weak Malian army --are ready for the withdrawal of thousands of French troops, fighter planes and helicopters which would give the Africans full responsibility against the Islamic extremists, who may strike the cities from their desert hideouts.

In Paris, U. S. Vice-President Joe Biden praised the French intervention in Mali while meeting with French President Francois Hollande.

"We applaud your decisiveness and, I might add, the capability of France's military forces," said Biden. "Your decisive action was not only in the interest of France but of the United States and everyone. We agreed on the need to, quickly as possible, establish an African-led mission to Mali and as quickly as prudent transition that mission to the UN."

Also in Paris, the Malian foreign minister Tieman Hubert Coulibaly told The Associated Press that the Malian army will be fighting with French and African troops against the Islamic radicals.

"We must continue pushing them (the extremists) north and then over there, there is a real need for a strong military force, air force, to destroy all the implementations around the mountains," said Coulibaly. "So ultimately, the real objective is to destroy all terrorist presence in northern Mali."

The French have ramped up their troop level to nearly 4,000 -- the number France once deployed in Afghanistan -- and nearly 3,800 African soldiers were in Mali as of Monday, the French Defence Ministry said. Some 1,800 Chadian soldiers were holding the northern town of Kidal while French troops held the airport.

In northern Mali, the price of food and fuel is rocketing up as a result of the conflict, the international aid organization Oxfam warned Monday.

Many market traders of Arab or Tuareg descent fled the area when French troops pushed out the Islamic extremists last week and the traders have not returned for fear of reprisals, said Oxfam, in a statement.

"If traders do not come back soon and flows of food into northern Mali remain as limited as they are now, then it is likely that markets will not be properly stocked and prices will stay high -- making it very difficult for people to get enough food to feed their families," said Philippe Conraud, Oxfam's country director in Mali.

"This phase of the war may almost be over, but the battle to build peace and stability has only just begun," said Conraud. "If people feel that their lives are at risk and that their families are not safe, they will not return to Mali. It's as simple as that."