The sources, who spoke to The Associated Press on condition of anonymity, said Capt. Lazaro de Betancourt sought asylum at the U.S. Embassy Sunday after a summit of the Association of Caribbean States.
If true, a defection would be at least a morale blow to the elite security corps that guards the Cuban leader. It might also give U.S. leaders information about Castro's habits and the security measures used to guard him.
Spokesmen at the embassy and the State Department in Washington would not comment on the reports.
``I'm not in a position to comment at this time,'' embassy spokesman Michael Stanton said in Santo Domingo. A State Department spokesman said he could neither confirm nor deny the report.
The captain was the second-in-command of a circle of bodyguards who protect Castro, the Dominican sources said. They added he is being housed in a U.S. diplomatic residence in Santo Domingo.
A senior official in the Dominican National Investigations Bureau said Dominican officials were proceeding with much caution because the Cuban was being protected by the U.S. Embassy, which he said also was in a difficult situation since the would-be defector was not in U.S. territory.
Castro kept an unusually low profile during the summit and left before it concluded.
A series of U.S.-backed Dominican governments shunned Castro for decades until the latest leader, the U.S.-educated President Leonel Fernandez, took over in 1996 and renewed relations with Cuba last year.
© Copyright 1999 The Associated Press