Former Honduran President Manuel Zelaya was stopped at the airport in the capital Tegucigalpa with $18,000 in cash in his bag, he said on Friday.
Zelaya was detained and released four hours later, the daily La Tribuna newspaper reported.
Zelaya said on Twitter that he was “unjustly detained” and that the money did not belong to him.
He was planning to fly to Mexico for a seminar with the PT political party, he wrote.
Honduran law states that anyone leaving the country can only take up to $10,000 with them.
There were protests at Toncontin airport.
According to local media reports, police used tear gas against demonstrators.
Zelaya was involved in the timber business before becoming president of Honduras in 2006.
He was ousted in 2009. He is now head of the left-wing Libre party.
