A husband and wife pleaded guilty Wednesday to being part of a Cuban spy ring, bringing to five the number of people who have admitted roles in the case.

Prosecutors promised Joseph Santos, 37, and his wife, Amarylis Silverio Santos, 37, that in return for the pleas they would argue against any effort to deport Mrs. Santos to her native Cuba. Her husband was born in the United States.

A portion of the agreement was kept secret until an unspecified ``personal security issue'' is resolved. U.S. District Judge Joan Lenard whispered the secret clause to the couple out of public earshot. Defense attorneys Gary Kollin and Alvin Entin and Assistant U.S. Attorney Caroline Heck Miller declined to comment.

Five more defendants, including three whose real identities are unknown, still face trial. Miller would not say whether she expects more guilty pleas.

The Santoses pleaded guilty to charges they conspired to become unregistered agents of a foreign government. They could face five years in jail, one year probation and a $250,000 fine.

Miller said the couple was recruited as intelligence agents in Cuba and dispatched to New Jersey in ``a nonactive capacity.'' Sometime in 1995, another ring member, Nilo Hernandez, 44, visited them and ordered them to move to Miami. Hernandez also has pleaded guilty.

The Santoses' main mission: To snoop around SouthCom, the Pentagon's Southern Command headquarters, which directs U.S. military operations in Latin America and the Caribbean. They were also told to get jobs at SouthCom, which moved to Miami-Dade from Panama over a year ago. They failed in that assignment.

Instead, Miller said the couple filled computer diskettes with ``voluminous reporting'' about the military headquarters, including descriptions of the industrial park area where SouthCom is located.

The Santoses stood somberly in court as they heard the government case through an interpreter. Under painstaking questioning by Judge Lenard, they admitted their guilt and signed a cooperation agreement that said they could get their sentences reduced in exchange for ``substantial assistance'' to the U.S. government.

The agreement also included a promise by federal authorities to recommend against Mrs. Santos' deportation if the Immigration and Naturalization Service -- another branch of the Justice Department -- decides to deport her. Mrs. Santos is a green-card holder, but a felony conviction could cause her to lose it.

Prosecutors allege the ring was divided between three ``officers'' and seven ``sub-agents,'' including the Santos couple, who were known by the code names Mario and Julia.

The officers came to this country from Cuba and took the identities of Americans who died as infants, the prosecution claims. They are identified in court complaints as John Does but lived in South Florida as Manuel Viramontes, 31, Luis Medina III, 30, and Ruben Campa, 33.

They still face trial, as do Rene Gonzalez, former Brothers to the Rescue pilot, and Antonio Guerrero, who allegedly used his civilian job at the U.S. Naval Air Station at Boca Chica to gather information.

Defense attorneys and prosecutors are still dueling over what documents will be released through discovery in the case. A hearing is scheduled for Nov. 2.

In addition to the Santoses and Hernandez, those who have pleaded guilty are Hernandez's wife, Linda, 42, and Alejandro Alonso, 39.

Of the 10 people charged in the case, at least five were born in the United States and another obtained U.S. citizenship more than 20 years ago.