TEHRAN, Iran (AP) _ A former Iranian intelligence agent said Saturday that he participated in the 1998 killings of dissident writers and intellectuals, state-run Iranian television reported.

Seyyed Mostafa Kazemi, the first of 17 defendants to testify, said during the closed court session that he had a role in ordering the killings, Iranian TV reported without providing any details.

Early last year, the Intelligence Ministry admitted that ``rogue agents'' had carried out dissident killings, a revelation that led to the intelligence minister's resignation.

The trial of the 17 people, including an unspecified number of former intelligence agents, opened Dec. 23 in a military court.

In November 1998, a husband and wife who ran a small dissident group were found stabbed to death in their Tehran home. The bodies of three other dissident writers and intellectuals were discovered in the capital a few weeks later.

The trial is limited to the deaths of four of the dissidents; the family of the fifth, writer Majid Sharif, has said he died of a heart attack.

Presiding judge Mohamed Reza Aghighi opened Saturday's third session of the trial by reiterating his decision that journalists and the public be barred from the courtroom, saying the trial could ``disturb public security,'' Iranian TV reported.

Families of the victims, reformist lawmakers and moderate newspapers have called for an open trial. The victims' families withdrew their lawyers from the case, saying they were boycotting the trial because they feared its ``conclusion will be against justice and the will of the nation.''

Earlier this month, the authorities detained a lawyer for two of the families, Naser Zarafshan, after he made a speech about the killings. He remains in detention.