Two US academics have pleaded not guilty to charges of working as covert Cuban agents who funneled information on US government officials and Cuban exile groups to Havana for nearly three decades.
Carlos Alvarez, a 61-year-old psychology professor at Florida International University, and his wife, Elsa Alvarez, 55, a social worker at the school, entered the pleas before a US magistrate in Miami, a court official said.
Both naturalized US citizens, the couple was indicted in December on charges of acting as foreign agents without notifying the US government.
Prosecutors say they used their positions at the university to attempt to recruit potential spies for Cuba and informed Havana on public attitudes and key players in Miami's exile community, the heart of opposition to Cuban President Fidel Castro and his communist government.
The indictment marked the latest prosecution of suspected Cuban spies.
The most prominent recent case was that of the "Cuban five," convicted in 2001 of infiltrating military bases and exile groups. An appeals court has agreed to review the convictions.
Carlos and Elsa Alvarez were being held without bond.