KEY WEST, Fla. -- An ultra-light plane en route from Havana, Cuba, was detained Wednesday afternoon at Key West International Airport, according to the Federal Aviation Administration.

A spokeswoman for the Monroe County Sheriff's Office said two men aboard the plane, registered to Wings For Earth, were stopped upon arrival and turned over to U.S. customs agents.

Officials said that the pilot and his passenger are both French nationals.

According to a police report from the Monroe County Sheriff's Office, the pilot told officials that he had flown from Cuba. When the pilot was informed that he was not permitted to fly directly from Cuba into the United States, the pilot said he was unaware of this. The pilot said that he had permission from the Cuban government to fly to the United States, and that he had contacted U.S. customs officials prior to his flight.

At that point, Customs and Border Protection agents took over the investigation, and the aircraft and luggage was examined.

According to the pilot, he and his passenger are adventurers. They planed to take the aircraft to Sebring, Fla., where it would be readied for a flight to Africa. Once there, the aircraft would be used to monitor wildlife and put to other ecological purposes.

Agents said that the men were never considered a threat and they would be released.