More than $11m (£8.8m) is missing from The Gambia's state coffers following the departure of long-time leader Yahya Jammeh, an adviser to President Adama Barrow has alleged.
Mai Ahmad Fatty said financial experts were trying to evaluate the exact loss.
Luxury cars and other items were reportedly loaded on to a Chadian cargo plane as Mr Jammeh left the country.
But another adviser to President Barrow, Halifa Sallah, later cast doubt on the claims of theft.
He said the police had been asked to investigate and they would determine if anything was missing. He said the central bank had "stated with clarity" that it was "functioning normally", as were other banks.
Mr Jammeh, who flew into exile after 22 years in power, has not commented on the allegations.
He had refused to accept the election results but finally left The Gambia after mediation by regional leaders and the threat of military intervention.
President Barrow remains in neighbouring Senegal and it is not clear when he will return.
However, West African troops entered the Gambian capital, Banjul, on Sunday to prepare for his arrival.
Cheering crowds gathered outside the State House to watch soldiers secure the building.
The Senegalese general leading the joint force from five African nations said they were controlling "strategic points to ensure the safety of the population and facilitate... Mr Barrow's assumption of his role".
Is $11m a lot for The Gambia?
Mr Fatty told reporters in the Senegalese capital Dakar that The Gambia was in financial distress.
"The coffers are virtually empty," he said. "It has been confirmed by technicians in the ministry of finance and the Central Bank of the Gambia."
He said Mr Jammeh had made off with nearly 500 million dalasis ($11.3m) in the past two weeks alone.
"That's a lot of money, considering that we spend about 200 million dalasis on required expenditure relating to payment of civil service and so forth," Mr Fatty told the BBC.
Mr Fatty said officials at The Gambia's main airport had been told not to let any of Mr Jammeh's belongings leave the country.
However, two Rolls-Royces and a Bentley were flown out over the weekend, and 10 others were at the airport waiting to go, reports the BBC's Umaru Fofana from Banjul.
Reports said some of the former leader's goods were in Guinea where Mr Jammeh had stopped on his journey into exile.
So where is Mr Jammeh now?
Mr Jammeh is reported to now be in Equatorial Guinea, although authorities there have not confirmed it.
He is suspected to have business interests in the oil-rich state, and is likely to be protected by President Teodoro Obiang Nguema.
The president has ruled the central African country since 1979, and is seen to be authoritarian, like Mr Jammeh.
Equatorial Guinea does not recognise the International Criminal Court (ICC) and has weak civil society and opposition groups, reducing the chances of the government coming under pressure to hand over Mr Jammeh to either the ICC or Mr Barrow's government for prosecution.
But could he be pursued?
The UN, African Union (AU) and Economic Community of West African States (Ecowas) had issued a joint statement, promising to protect Mr Jammeh's rights "as a citizen, a party leader and a former Head of State".
They also gave an assurance that his "lawful" assets would not be seized, and his exile was "temporary".
However, Mr Fatty distanced Mr Barrow from such assurances.
"As far as we're concerned, it doesn't exist,'' he was quoted by the Associated Press news agency as saying.
Did Mr Jammeh commit human rights abuses?
The Gambian security forces, especially intelligence agents known as the Jungulers, were repeatedly accused of torturing opponents, detaining them without trial or killing them.
Campaign group Human Rights Watch, in a 2015 report, said torture methods included rape, near-suffocation with plastic bags and electric shocks.
One man was reportedly forced to drink cooking oil, while others had melted plastic bags dripped onto their skin, it said.
Mr Jammeh had also implemented tough measures against gay people. He called them "vermin" and threatened to slit their throats.
Mr Barrow has said he will establish a Truth and Reconciliation Commission to investigate abuses.
Why is the president still in Senegal?
Ecowas commission chairman Marcel Alain de Souza said that part of the security forces needed to be "immobilised" and Mr Jammeh had also hired mercenaries during the stand-off, AP reports.
So, Mr Barrow is likely to return only when Ecowas thinks it is safe.
While army chief Ousman Badjie has pledged his loyalty to Mr Barrow, it is unclear whether the elite presidential guards support Mr Barrow.
Since Mr Jammeh's defeat, some members of the new governing coalition have feared the long-term leader would withdraw to his farm in his home village of Kanilai, near the border with southern Senegal, and launch a rebellion.
A top Gambian army commander, who is with the regional force, told the BBC that no heavy weapons were found at the presidential mansion.
There were concerns that weapons may have been hidden or taken to Kanilai for "future sinister use", the commander added.