Former Honduran president Manuel Zelaya was stopped at an airport in the capital Tegucigalpa with 18,000 dollars in cash in his bag on Friday.
Zelaya was detained and released four hours later, the daily La Tribuna newspaper reported.
On his part, ex president Zelaya said on Twitter that he was “unjustly detained” and that the money did not belong to him.
He said 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 dollars with them.
News of the arrest sparked immediately protests at the Toncontin airport.
According to local media reports, police had to use 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.
