LAGOS, Nigeria — A Nigerian army memo orders officers to prepare a battalion of 800 troops for a possible military intervention in Gambia, where the longtime leader has refused to accept his election loss and step down.

West Africa’s regional bloc, the Economic Community of West African States, has said it has a standby military force ready to enter Gambia if President Yahya Jammeh does not cede power when his mandate expires next Thursday. Jammeh, who has ruled since he took power in a 1994 military coup, is challenging his Dec. 1 loss.

The Nigerian memo dated Wednesday and seen by The Associated Press is signed by the chief of army staff, Lt. Gen. Tukur Buratai, and describes the force as ECOMIG, or ECOWAS Mission in Gambia.

Army spokesman Col. Sani Kukasheka Usman denies Nigeria’s military is readying such a force.

Nigeria’s President Muhammadu Buhari led a regional delegation to Gambia on Friday to try to persuade Jammeh to step down. Nigerian legislators have voted to allow Buhari to offer asylum to Jammeh as the region seeks a peaceful solution to the crisis.

The West African regional bloc has said the standby force would be led by Senegal, which almost completely surrounds Gambia.

Gambia, with just 1.9 million people, had an army of just 900 troops as of 2013, according to the South Africa-based military news site defenceWeb.

Nigeria’s memo indicates the 800 troops will come from different battalions. That is probably because Nigerian security forces already are stretched, fighting Boko Haram’s Islamic uprising in the northeast and deployed against oil militants in the south and separatists in the southeast.