Gambia ex-leader 'made off with millions'

Exiled Gambian ruler Yahya Jammeh stole millions of dollars in his final weeks in power, plundering the state coffers and shipping out luxury vehicles by cargo plane, an adviser for the new president says.

Meanwhile, a regional military force has rolled in to secure this tiny West African nation so democratically elected President Adama Barrow can return home.

He remains in neighbouring Senegal, where he took the oath of office on Thursday because of concerns for his safety.

At a news conference in the Senegalese capital, Barrow's special adviser Mai Ahmad Fatty told journalists the president "will return home as soon as possible".

Underscoring the challenges facing the new administration, Fatty confirmed Jammeh made off with more than $US11.4 million ($A15.1 million) during a two-week period alone.

That is only what they have discovered so far since Jammeh and his family took an offer of exile after more than 22 years in power and departed late on Saturday.

"The Gambia is in financial distress. The coffers are virtually empty. That is a state of fact," Fatty said.

Fatty also confirmed a Chadian cargo plane had transported luxury goods out of the country on Jammeh's behalf in his final hours in power, including an unknown number of vehicles.

The unpredictable Jammeh, known for startling declarations such as his claim that bananas and herbal rubs could cure AIDS, went into exile under mounting international pressure, with a wave to supporters as soldiers wept.

He is now in Equatorial Guinea, home to Africa's longest-serving ruler and not a state party to the International Criminal Court.

Jammeh's dramatic about-face on his December election loss to Barrow, at first conceding and then challenging the vote, appeared to be the final straw for the international community, which had been alarmed by his moves in recent years to declare an Islamic republic and leave the Commonwealth and the ICC.

The regional military force that had been poised to force out Jammeh if diplomatic efforts failed rolled into Gambia's capital, Banjul, on Sunday night to secure it for Barrow's arrival.

Hundreds greeted the force's approach to State House, cheering and dancing.

The force, including troops from Senegal, Nigeria, Ghana and Mali, will remain in the country "until such time the security general situation is comprehensively redressed", Barrow said in a statement.