The prosecutor of Tehran's military tribunal, Mohammed Niazi, said the trial would be held in public unless the judge decides it would be against Iran's national security interests.

Iran's political moderates, led by President Mohammad Khatami, have demanded that the case should be heard in open court.

Mr Niazi said those charged with the murders were not members of any particular faction. But he alleged that some of the ten suspects may have been agents from the powerful Intelligence Ministry, which is controlled by the conservatives, acting without the authority of their superiors.

Public uproar

Correspondents say the murders have caused a public uproar and intensified the struggle between conservatives and the moderates in the Iranian leadership, with each side blaming the other for the killings.

The row intensified after an Iranian state television programme alleged that supporters of President Khatami were behind the killings.

The head of Iran's state TV and radio, Ali Larijani, was subsequently barred from attending cabinet meetings, although he has now issued an statement regretting the allegations.

Apology demanded

Mr Larijani said state television's policy was to create an atmosphere of unity, rather than division, and regretted that this particular programme had been contrary to this policy. For this reason, he said, it was essential to deal with those responsible.

Mr Larijani is appointed by Iran's supreme leader, Ayatollah Khamenei, who is regarded as a supporter of the conservative faction.