BAMAKO: French and Malian troops pushed north towards the key Islamist strongholds in northern Mali, as west African defence chiefs gathered in Ivory Coast Saturday to review plans to deploy a regional intervention force.

The emergency meeting in Abidjan is to look at how to get soldiers from the African force on the ground as quickly as possible.

Although the Economic Community of West African States has pledged more than 4,500 soldiers to help Mali retake its Islamist-occupied north, their deployment has been delayed by financing and logistical problems.

While a fraction of the African forces have arrived in Bamako and are slowly deploying elsewhere, the French and Malian forces have done all of the fighting.

On Friday, the French and Malian forces captured Hombori, another northern town in their advance on the Islamist stronghold of Gao.

A Malian security source said the troops would press on to Gao. Along with Kidal and Timbuktu, it is one of the three major northern towns where the Al Qaeda-linked Islamists have imposed a harsh form of Islamic law (sharia) for 10 months.

To the centre, the source added, French-led forces who on Monday had recaptured the town of Diabaly were pushing northeast towards the town of Lere with the aim of taking control of Timbuktu, still further north.

In April last year, Gao, Timbuktu and Kidal were seized by an alliance of Tuareg rebels -- who wanted to declare an independent homeland in the north -- and hardline Islamist groups.

The Islamists quickly sidelined the Tuaregs to implement their own Islamic agenda. They imposed a harsh interpretation of sharia law, flogging, stoning and executing transgressors, forbidding music and television and forcing women to wear veils.

France swept to the aid of the weakened Malian army on January 11 as the Islamists pushed south towards the capital Bamako. French airstrikes on Gao and Timbuktu forced the Islamists to flee into the desert surrounding wilderness.

France has already deployed 2,300 troops to Mali and defence officials acknowledge the force is likely to exceed the 2,500 soldiers that were initially presented as the upper limit.

Plans for a second front against the Islamists were hit on Friday when the insurgents bombed a key bridge at Tassiga. It would have given African troops gathering in Niger to the south easy access to Gao.

More than than 2,000 Chadian soldiers have arrived in Niger, joining 500 soldiers from the country's army, to tackle the Islamist forces in Mali.

-- Fears over regional food crisis --

Aid agencies have expressed increasing concern about the growing food crisis for civilians in the vast semi-arid north of Mali and the drought-wracked Sahel as a whole.

A statement from French aid group Action Against Hunger (ACF) raised fears "that an armed ground intervention from Niger will cut the last access route to supply basic goods (food and medicine) to people in the region."

Christian Aid expressed similar fears.

"The current food crisis has already brought suffering to more than 18 million people across the region," said Yacouba Kone, its Mali country director.

"The more people are forced to flee the mounting military offensive in the north, the more market gardens are being abandoned and the less vegetables are being produced for child nutrition."

Fresh evidence emerged meanwhile of killings carried out by the Islamists.

UNHCR spokeswoman Melissa Fleming said one person who had fled the city of Gao had described seeing "a woman being executed summarily for refusing to show the contents of her bag to a rebel fighter as she tried to board a bus".

Meanwhile, US President Barack Obama backed France's military intervention during a telephone conversation with French President Francois Hollande.

"The president expressed his support for France's leadership of the international community's efforts to deny terrorists a safe haven in Mali," said a White House statement.

In the Ethiopian capital Addis Ababa, the African Union said it would be calling on its members to bolster the strength of AFISMA, the African-led force for Mali.

The AU would also seek support from the United Nations for the operation, in the form of transport, medicine and field hospitals, peace and security commissioner Ramtane Lamamra told reporters.

France has asked several Western countries and others to provide logistical support such as planes to allow aerial refuelling, sources close to Defence Minister Jean-Yves Le Drian said.

Britain, which has already contributed two C-17 transport planes to airlift military equipment, said it had sent a surveillance plane to aid operations.