TEGUCIGALPA - President Ricardo Maduro said Tuesday he was demanding that the United States and Panama explain how a man facing terrorism charges may have been allowed to fly to Honduras on a false U.S. passport.

Maduro told reporters he had ordered ''an immediate investigation'' into the case of Luis Posada Carriles, who was freed from prison Thursday by Panamanian President Mireya Moscoso. Officials say there is strong evidence that the former CIA operative and longtime foe of Cuban President Fidel Castro got off that plane in Honduras, leaving three liberated colleagues to fly on to Miami. U.S. officials have denied any role in the pardon of Posada.

Maduro said Posada would be treated as an illegal immigrant if caught. The 76-year-old still faces charges in Venezuela of masterminding the 1976 bombing of a Cuban commercial airliner that killed 73 people.

Meanwhile, in Havana, the Cuban government said Tuesday it would not send any representatives to the Sept. 1 inauguration of Panama's new president because of the recent rupture of relations between the countries.

Cuba broke diplomatic ties with Panama last Thursday after the pardon.