DAKAR, Senegal (AP) — Gambia's political opposition says long-time ruler Yahya Jammeh could be considered a rebel leader if he takes up arms and doesn't step down later this month.

Halifa Sallah, spokesman for Gambia's opposition coalition, gave the firm warning Monday, days after the president railed against the West African regional bloc that has urged him to step down.

Jammeh vowed that any presence of foreign troops in the tiny West African nation would be tantamount to an act of war.

The president's party is challenging the results in the Dec. 1 election won by opposition coalition candidate Adama Barrow.

Meanwhile, President-elect Barrow says he is planning a Jan. 19 inauguration. He has urged Jammeh to open communication channels and peacefully relinquish power after 22 years in office.