West Africa's regional bloc needs up to $2.6 billion annually to establish a 5,000-strong security force to combat terrorism, according to one of the options being considered by defence officials at a meeting on Thursday.

Defence and finance ministers from the Economic Community of West African States (ECOWAS) were meeting in the Nigerian capital Abuja to decide on the size of a potential force and how much would be required to fund it.

Coup-hit West Africa is grappling with a raft of political crises that have hurt regional cooperation. In January, military-ruled Niger, Burkina Faso and Mali decided to exit the 15-member union.

Since 2020, soldiers in the three countries have carried out coups blaming civilian leaders for allowing Islamist militants to gain ground. Once in power, juntas have torn up defence agreements with the U.S., French and U.N. forces and invited Russians to take their place.

Nigerian Defence Minister Mohammed Badaru Abubakar told the meeting that there were two options for a regional force: One which would cost $2.6 billion annually for a brigade of 5,000 and another that would cost $481 million for 1,500 troops.

"These figures underscore the gravity of the task before us," Abubakar said. "It is therefore imperative that we critically review the options considering the current challenges confronting our region and the financial concerns facing our various members states."

Abubakar added that the regional force would not be used to reverse coups but limited to fighting terrorism. Each member state would be expected to contribute a quota, he said.

ECOWAS commission president Omar Touray said members under suspension would not be excluded from the regional force.

"It is believed we cannot fight terrorism alone while others are not participating," Touray said.

"Although, other countries might be under suspension but they should be allowed to take part in meetings related to security, that is why we have invited all 15 member states to attend this crucial meeting."