A U.S. government witness is set to take the stand for the seventh straight day Tuesday in a perjury trial against a former CIA operative who spent a lifetime opposing Fidel Castro.

Gilberto Abascal will face more questions from defense attorneys accusing him of being a spy for the Cuban government and of resenting their client, Luis Posada Carriles. The prosecution admits Cuba-born Abascal is a government agent — but for Washington, not Havana. U.S. attorneys say he was paid about $80,000 as a federal informant testifying against Posada. They laugh off claims he's a double agent.

Abascal's testimony is important to the 11 counts of perjury, obstruction and immigration fraud against the 82-year-old Posada, who is accused of lying during immigration hearings about how he sneaked into the United States in 2005, and also failing to acknowledge his role in a series of 1997 Cuban hotel bombings.

The 45-year-old Abascal testified that he was the mechanic aboard a shrimp boat-turned-yacht that sailed to Mexico, picked up Posada and helped him slip ashore in Miami in March 2005. Posada told immigration authorities that he paid a people smuggler to drive him from Honduras across the Texas border.

In an effort to discredit Abascal's story, Posada attorney Arturo Hernandez has pressed Abascal on his past. U.S. Attorney Jerome Teresinski objected to those questions, appealing to U.S. District Judge Kathleen Cardone without the jury present Monday.

"Counsel's argument reads like a John Grisham novel. It's fiction," Teresinski said. "He wants to put Cuba on trial. He wants to put Fidel Castro on trial."

Cardone overruled him.

Once the jury was seated, Hernandez asked why Abascal made four visits to Cuba in 2004 and 2005. He said that someone with known ties to Posada — who is public enemy No. 1 in Cuba — could not have been allowed to visit the island unless he was working for the Cuban government. He also suggested Abascal might have been a smuggler.

"The only thing I have ever smuggled is Posada Carriles," Abascal shot back.

Abascal says he first attempted to flee Cuba in 1993. He spent two years in prison for trying, then was granted U.S. asylum in 1999.

But he said he was homesick, and soon attempted to return to his country by boat. That vessel was stopped by the U.S. Coast Guard, which discovered photos of a Florida training site run by the violent anti-Castro exile group Alpha 66.

Hernandez alleged that Abascal was carrying those pictures to his superiors in the Cuban government. The witness said they were meant to encourage internal government resistance groups on the island.

During later questioning by Teresinski, Abascal explained that he visited Cuba frequently because his mother was ill. Asked if he was a Cuban spy, Abascal calmly said, "no."

After participating indirectly in the Bay of Pigs invasion, Posada worked for the CIA and later served as head of Venezuelan intelligence. In the 1980s, he helped support U.S.-backed Nicaraguan "contra" rebels.

Posada was imprisoned in Panama for a 2000 plot to kill Castro during a visit there, but was eventually pardoned and arrived in the U.S., prompting the current charges against him. He was jailed in El Paso but released in 2007 and has been living in Miami.

Cuba and Venezuela accuse Posada not only of the 1997 Cuban hotel bombings, but also of organizing an explosion aboard a Cuban airliner in 1976 that killed 73 people. A U.S. immigration judge has previously ruled that he couldn't be deported to either country because of fears of torture.