MIAMI -- A college professor and his wife, a university administrator, have been charged with being illegal agents of Cuba's communist government run by President Fidel Castro, according to court documents unsealed Monday.

Carlos Alvarez, 61, a psychology professor at Florida International University, and his wife, 55-year-old Elsa Alvarez, have been charged with acting as agents of Cuba without registering with the U.S. government as required.

Images: Pair Accused Of Spying For 30 Years

They were ordered held without bond by U.S. Magistrate Judge Andrea Simonton, who rejected pleas by their attorneys for release on bail. Simonton said she agreed with federal prosecutors that the couple would leave their five children and return to Cuba if released.

Neither defendant entered a plea, and another hearing was set for Jan. 19. They were arrested Friday, months after giving voluntary statements this summer about their contacts with Cuba to the FBI, prosecutors said.

Brian Frazier, an assistant U.S. attorney, said that Alvarez had spied for Cuba since 1977 and his wife since 1982. Neither was charged with the more serious offense of espionage, and FBI agents acknowledged there is not evidence that they provided classified or military information to Cuba.

Much of what they provided, according to Frazier, involved information about the U.S. political situation, prominent Cuban-Americans in South Florida and the names of at least one FBI agent. Frazier said the two used an elaborate encryption system provided by Cuba to communicate with their handlers via short-wave radio and carried messages to and from Cuba using their academic covers.

"These were highly placed and very well-regarded operatives in the United States," Frazier said.

Alvarez is identified on the Florida International Web site as an associate professor in the Educational Leadership and Policy Studies Department. Elsa Alvarez is described as a coordinator in the social work training program, specializing in psychological treatment, crisis intervention and group psychotherapy.

U.S. Attorney R. Alexander Acosta, the FBI and the Naval Criminal Investigative Service scheduled a news conference for later Monday to discuss the case.

The indictment marks the latest turn in the cloak-and-dagger underworld of espionage between the United States and Cuba, much of it taking place in South Florida where thousands of Cuban exiles live.

In August, the convictions and sentences of five alleged Cuban spies were thrown out by a three-judge panel of the 11th U.S. Circuit Court of Appeals, which ruled that the five were unfairly tried because of intense publicity, community prejudice and inflammatory remarks by prosecutors.

They were accused of being part of the Wasp Network of Cuban spies operating on U.S. soil. They admitted being agents of Cuba but insisted they were spying on Cuban exiles opposed to Castro, not on the United States itself.

The full 11th Circuit has agreed to rehear the arguments on whether the five got a fair trial.