French photographer Pierre Golendorf, who spent 2 1/2-years in a Cuban jail, and Cuban artist Lazaro Jordana, jailed four years for illegally leaving the country, filed two of the complaints last month.
Both men accuse Castro of crimes against humanity, including torture and murder.
A third complaint, for drug trafficking, was filed by Ileana de la Guardia, the exiled daughter of Cuban Col. Antonio de la Guardia, who was convicted and executed in 1989 along with three other officials for allegedly smuggling drugs.
De la Guardia said earlier this year that Cuban drug trafficking ``was a matter of state, organized by the highest echelons of power in the country. ...It's impossible that Fidel Castro was unaware of this.''
The prosecutor's office rejected the complaints in part on the grounds that they went beyond its authority, said the sources, speaking on condition of anonymity.
The prosecutor ruled that he was not competent to handle the matter because, in France, the notion of ``crimes against humanity'' is reserved only to World War II crimes as defined by the Nuremberg Tribunal, the sources said.
In the drug case, the prosecutor ruled that the complaint did not hold up because Ileana de la Guardia could not show that she was hurt by the drug trafficking.
Investigations, however, could still move forward if the magistrate in the case rejects the prosecutor's opinion.
In November, a Spanish court rejected petition by a Cuban exile group for a probe into allegations of genocide, terrorism and torture filed against Castro.
© Copyright 1999 The Associated Press