LIBREVILLE • A West African regional force set up to fight Boko Haram will need "local intelligence" to root out extremist insurgents forced on the run by national army offensives, security experts say.

"With Boko Haram reverting to acts of terrorism and hit-and-run armed raids... Nigeria and its allies will need to secure a reliable and extensive local intelligence network," said Mr Ryan Cummings of security firm Red24.

Nigeria's neighbours Chad, Cameroon and Niger, which have all suffered attacks by Boko Haram, launched a regional force earlier this year to end a conflict that has claimed more than 15,000 lives since 2009. But the Joint Multinational Intervention Force (MNJTF), which also includes Benin, and is expected to number some 8,700 troops and policemen, has yet to go into action.

Meanwhile, national armies have succeeded in scattering Boko Haram militants to remote, inaccessible areas. Many of the insurgents are hiding in Lake Chad, a shallow, marshy water body dotted with hundreds of islets, and in Nigeria's Sambisa Forest near the border with Cameroon.

The extremists once controlled large swathes of territory and key towns such as Gwoza and Baga in north-eastern Nigeria where they proclaimed a caliphate before pledging allegiance to the militant group, Islamic State in Iraq and Syria. Now in disarray, they have begun conducting suicide missions into cities and towns, often using very young girls who detonate themselves in crowded areas.

The MNJTF was agreed in May last year in the wake of the kidnapping of more than 200 Nigerian schoolgirls that shocked the world.

The five countries have yet to "determine which areas of Nigeria and neighbouring countries the multinational force will be allowed to operate in", Mr Cummings said.

The delay may also be explained by funding problems for a force almost entirely financed by its member states.

The United States has pledged US$5 million (S$6.9 million) to MNJTF, while France is providing technical assistance.

AGENCE FRANCE-PRESSE, REUTERS