Customs agents detained a plane chartered by Air Panama to search for any U.S. currency being taken illegally out of the country Wednesday but found none and sent the aircraft on its way, a spokesman said. ``U.S. Customs had some information that there might possibly be an outbound currency violation connected with the flight,'' spokesman Michael Sheehan said. The chartered Boeing 707 was scheduled to carry military and police-type uniforms, small machinery and other merchandise to Panama City, Sheehan said. It was detained for four hours Panama's national currency is the U.S. dollar, and the cash supply has been drying up because of a dispute over control of the Panamanian government. Panama keeps an estimated $50 million on deposit in American banks, but U.S. judges froze assets in banks in Miami and New York to prevent the government of Gen. Manuel Antonio Noriega from withdrawing funds.