Former Honduran president Manuel Zelaya says he was "unjustly" detained at the Central American nation's Toncontin International Airport for carrying $US18,000 ($A24,400) in cash, which he says was not his.
"Obviously someone must have put it in my belongings. I have traveled 400 times and I know that you cannot travel with that amount of money. It is necessary to investigate who put that money in my belongings," Zelaya told local media.
Earlier, he wrote on Twitter he had been "unjustly detained" after a search of his carry-on luggage. But Honduras' public prosecutor's office said he was not "unjustly detained".
"What is happening is what the law says, which means documenting (what happened) and once that is complete and signed by former president Zelaya, where he states the money is not his, he can easily go," a spokesman told Reuters.
Zelaya, who led Honduras from 2006 to 2009, was deposed by the military in a coup as he was preparing to hold a referendum on presidential re-election, which his opponents said was a ploy to stay in power.
He remains active in politics as leader of the leftist Partido Libertad y Refundacion party.
The former president told local media he planned to travel to Houston, Texas, before flying to Mexico to give a conference on Saturday.
Honduran laws allow for a maximum of $US10,000 to be taken out the country, which must be declared.
Australian Associated Press