BAMAKO (Reuters) - West Africa's regional bloc has put standby forces "on alert" in case Gambian president Yahya Jammeh does not step down when his mandate ends on Jan. 19, president of the ECOWAS commission Marcel de Souza said late on Thursday.
Jammeh has vowed to stay in power despite losing a Dec. 1 election to rival Adama Barrow. ECOWAS has previously warned him that it would take "all necessary actions" to resolve the impasse.
Barrow's surprise victory and Jammeh's initial decision to concede was seen across Africa as a moment of hope until the president reversed his position a week later. His party is now challenging the result in Gambia's Supreme Court.
Regional leaders have mandated Nigerian President Muhammadu Buhari to mediate the crisis and are offering Jammeh an "honourable exit", but if he does not take it then forces could be deployed, De Souza said on Malian state television.
"... we have put standby forces on alert if he does not take it on Jan 19 when his mandate ends...," De Souza said.
Diplomats say ECOWAS would probably seek approval from the U.N. Security Council for the use of force. Senegal is a likely candidate for leadership of any African intervention force given its position as Gambia's only territorial neighbour.
Senegal has indicated that military action would be a last resort and President Macky Sall said earlier this week that he thought Buhari would be able to make Jammeh see reason.
Reporting by Tiemoko Diallo; Writing by Nellie Peyton; Editing by Alison Williams