French troops, seen through a night vision device, advance towards Timbuktu in this undated picture provided by the French Military audiovisual service (ECPAD) January 29, 2013. French and Malian troops retook control of Timbuktu, a UNESCO World Heritage site, after Islamist rebel occupiers fled the ancient Sahara trading town and torched several buildings, including a library holding priceless manuscripts. REUTERS/Arnaud Roine/ECPAD/Handout (MALI - Tags: MILITARY POLITICS TPX IMAGES OF THE DAY)

Douentza/Gao, Mali - French-backed Malian troops searched house-to-house in Gao and Timbuktu on Tuesday, uncovering arms and explosives abandoned by Islamist fighters, and France said it would look to hand over longer-term security operations to African troops.

French and Malian troops retook the two Saharan towns in northern Mali virtually unopposed at the weekend after an 18-day French-led offensive that has pushed back the al Qaeda-allied militants into hideouts in the deserts and mountains.

Malian government soldiers were combing through the Niger River towns and their neighbourhoods of dusty alleys and mud-brick homes. In Gao, they arrested at least five suspected Islamist rebels and sympathisers, turned over by local people, and uncovered caches of weapons and counterfeit money.

Residents reported some looting of shops in Timbuktu owned by Arabs and Tuaregs suspected of having helped the Islamists who had occupied the world-famous seat of Islamic learning, a UNESCO World Heritage site, since last year.

Fleeing Islamist fighters torched a Timbuktu library holding priceless ancient manuscripts, damaging many.

Malian army sources told Reuters pockets of armed Islamist fighters, on foot to avoid French air strikes, were still hiding in the savannah and deserts around Gao and Timbuktu and near main roads leading to them, parts of which were still unsafe.

The West African country has been in political limbo since a March 2012 coup triggered the rebel takeover of the north.

France, which has sent around 3,000 troops to Mali at the request of its government, says it wants to pass the baton of longer-term security operations there to a larger U.N.-backed African force, known as AFISMA, being deployed in the country.

The French, anxious not to get bogged down in a messy counter-insurgency war in their former Sahel colony, have made clear that while the first phase of liberating the biggest north Mali towns may be over, a more difficult challenge to flush the Islamist desert insurgents from their hideouts still remains.

“We will stay as long as necessary. We want to make sure there will be a good handover between France and AFISMA. There is no question of us getting stuck in the mud,” French Foreign Minister Laurent Fabius said in Ethiopia's capital Addis Ababa.

Also in Addis Ababa, Malian interim President Dioncounda Traore announced his government would aim to organise “credible” elections for July 31, a demand made by major western backers of the anti-rebel operation.

Fabius was attending a meeting of international donors there who were asked to foot the bill for the African intervention force for Mali, which Ivory Coast President Alassane Ouattara said would exceed 8,000 troops and cost nearly $1 billion.

The United States and European governments are backing the French and African military operation against the Islamist rebels in northern Mali with logistical, airlift and intelligence support, but they are not sending combat troops.

They see the intervention as vital to root out a hotbed of al Qaeda-allied insurgency in West Africa that could threaten African governments and western interests from Mauritania to oil-producing Nigeria, as well as strike directly in Europe.

Britain boosted an offer of aid to help France's effort in Mali and pledged troops to assist other African governments in the region. Up to 240 British troops could be deployed as part of two missions to train African troops.

The United States also extended deployment of surveillance drones that could track down rebel bases and columns in the Sahara desert. Mali's neighbour Niger on Tuesday gave permission for U.S. drones to fly from its territory.

The bulk of the planned African intervention force for Mali - to be comprised mostly of West African troops - is still struggling to get into the country, hampered by shortages of kit and supplies and lack of airlift capacity to fly the troops in.

Around 2,000 are already on the ground. Burkina Faso, Benin, Nigeria, Senegal, Togo, Niger and Chad are providing soldiers for the AFISMA force. Burundi and other nations have also pledged to contribute.

Hundreds of soldiers from Chad and Niger with desert warfare experience have crossed into Mali to join the French and Malian operations against the retreating Islamist rebels, who have pulled back to the rugged northeast mountains of the Adrar des Ifoghas range on the border with Algeria.

The commander of the Chadian forces in Mali, Abdu Aziz Hassan Adam, told Reuters in Gao his forces were ready to “sweep the terrorists out of the north of Mali”. “They are a threat for all the countries of the world,” he added.

Besides Gao and Timbuktu, another major Malian Saharan town, Kidal, had also been in Islamist insurgent hands but MNLA Tuareg rebels said on Monday they had taken control there after the Islamists left.

The MNLA's Tuareg leaders, whose pro-independence rebellion that seized the northern half of Mali last year was subsequently hijacked by Islamist radicals, said their desert fighters were ready to join the French-led campaign against “terrorist organisations” - a reference to al Qaeda and its allies.

But they also asked for direct negotiations with the Malian government about their autonomy demands.

Chadian troops were expected to deploy up to Kidal in the northeast to secure it, officials in Niger said.

Besides the funds being pledged at the Addis Ababa donors' conference for the African force - which seem likely to fall short of the nearly $1 billion requirement estimated by African leaders - the International Monetary Fund has also approved a rapid loan of $18.4 million for the Malian government. - Reuters