TEHRAN — The Iranian scientist who American officials say defected to the United States only to be pressured by Iran to return home has made his first appearance since his arrival last week in Tehran, adding details to what he says was his abduction, psychological torture and eventual release by American intelligence agents.

A videotaped interview with the scientist, Shahram Amiri, broadcast on Iran’s state television Saturday evening, showed him against a black backdrop and under bright studio lights, beads of sweat glistening on his forehead.

Mr. Amiri accused American agents of trying to coerce him to confess to being a spy so they could try to exchange him for three young hikers from the United States who have been held by Iran since they wandered over the border from Iraq in July 2009.

“They told me that if I confess to being an Iranian intelligence agent, they could trade me with the three spies who were caught near the Iraqi border,” Mr. Amiri told the interviewer, who then asked him whether the United States agents had specifically used the term “spy” to describe the hikers.

“Yes, they used the word ‘spy’ and told me that trading spies between countries is quite normal,” Mr. Amiri replied.

Mr. Amiri has said that he was kidnapped by the Central Intelligence Agency and Saudi agents while on a pilgrimage in Saudi Arabia in June 2009, then tortured by C.I.A. agents to reveal secrets about Iran’s nuclear program, although he insists he knew nothing about the program.