ADDIS ABABA (Reuters) - The African Union (AU) might grant a mandate as early as this week for a regional military force to combat Islamist Boko Haram militants, a vital step towards securing U.N. Security Council backing, a diplomat said on Tuesday.

Nigeria, Cameroon, Niger, Chad and Benin agreed in Niger’s capital Niamey this month that the AU would seek U.N. support for the operation to take on Boko Haram, which is fighting to create an Islamic emirate in northern Nigeria.

The Islamists have made incursions into neighboring Cameroon and threaten the stability of a region that includes Niger and Chad. Benin lies on Nigeria’s western border.

Smail Chergui, the commissioner of the AU’s Peace and Security Council, said tackling Boko Haram was on the agenda for talks in Addis Ababa, where African leaders hold a summit meeting later this week. He did not give details.

A diplomat, asking not to be identified, told Reuters the AU’s Peace and Security Council might approve the mandate for the multinational force when it meets on Thursday evening.

He said the roughly 3,000-strong force would be “mandated by the AU and supported by the U.N.”, noting that the aim would be to obtain U.N. Security Council backing “as soon as possible”.

A U.N. mandate could help draw in international assistance for the African regional force.

The African group plans to meet in early February in Cameroon to draw up a “concept of operations” to cover strategy, rules of engagement, command and control, and related issues.

Each of the five nations would contribute a battalion - 500 soldiers from Benin and about 700 from each of the other four - and each contingent would based within its national borders with operations coordinated from Chad’s capital N’Djamena.