A Tanzanian man who admitted he provided explosives used in attacks on two U.S. embassies in Africa wanted to "clear his heart" by testifying against the first Guantanamo detainee to be tried in a civilian court, an FBI agent said Tuesday.

The agent, Philip Swabsin, described his interviews with the Tanzanian man, Hussein Abebe, during a hearing to determine whether Abebe can testify at the trial of detainee Ahmed Khalfan Ghailani. Ghailani is charged in the 1998 bombings, which killed 224 people, including 12 Americans.

Defense lawyers oppose the government's plan to call Abebe as a witness on the grounds that prosecutors coerced him into testifying. Authorities learned about Abebe only after Ghailani made statements when he was subjected to "enhanced interrogation" at a CIA-run camp overseas after his 2004 arrest, the defense attorneys say. After the Sept. 11 attacks, the CIA used 10 harsh methods, including waterboarding, a form of simulated drowning.

Swabsin said he met Abebe in August 2006 at an oceanfront home where he was being held after he was picked up by Tanzanian security and intelligence officers. He said he read him his legal rights immediately after introducing himself.

After questioning Abebe for two days, Swabsin said he asked Abebe if he would be willing to testify in Tanzania or in the United States and found an eager cooperator who viewed testifying as an "opportunity to clear his heart, his thoughts and his conscience."

Swabsin said he met with Abebe again in November 2006 and was "taken a bit aback" when Abebe asked if he would qualify for a reward for his testimony.

"Personally, I found it a bit incredulous," Swabsin said, noting that Abebe's request was met by chuckles from investigators. He said he told Abebe he "should consider himself fortunate he is a free man, that he's not criminally charged."

Swabsin's testimony before U.S. District Judge Lewis A. Kaplan in Manhattan was the beginning of a two-day hearing that was also expected to include testimony from Abebe.

The courtroom was closed to the public Tuesday afternoon after a prosecutor said the testimony of another agent from a different agency, presumably the CIA, would be testifying about classified information.

Legal issues — such as how overseas CIA interrogations of Guantanamo detainees might affect their trials in civilian courts — are being staged for the first time in the Ghailani case, setting precedents for how they are likely to be treated in subsequent trials.

Defense lawyers have already lost their argument that charges against Ghailani should be thrown out because he was not brought to trial sooner.

Swabsin said he never saw statements Ghailani made to the CIA and believed that they remained classified. Prosecutors have said they have no plans to use Ghailani's statements to the CIA at his trial, unless he testifies.

Defense lawyer Peter Quijano asked Swabsin if he was aware that Abebe "lived in dread that someday he would be arrested by Tanzanian police because he supplied explosives to Ghailani."

"Yes," Swabsin answered.

Quijano asked if he knew that Abebe was aware that Ghailani was a suspect in the bombings when he saw his photograph in television accounts of the attacks.

"He advised us he was scared," Swabsin said.

Questioning of prospective jurors is expected to begin on Sept. 27, and opening statements are likely to occur in the week afterwards. The trial is expected to last about three months.

Four men already are serving life sentences in the embassy attacks after they were convicted in 2001.