By Jim Muir BBC correspondent, Tehran

Student leaders in Tehran have been arrested following demonstrations against the death sentence for apostasy passed this month on a liberal university lecturer, Hashem Aghajari.

At least six student activists were detained by plainclothes police on the orders of a revolutionary court.

Initially, it was unclear who had detained the student leaders, or why.

Eyewitnesses said one of them, Abdullah Mo'meni, was simply grabbed in the street and bundled into a civilian car by men in plain clothes who sprayed his companion in the face with teargas.

Anger

Time is running out for Aghajari to appeal

Later it was confirmed that the arrests had been carried out on the orders of a branch of the Revolutionary Court, and that they were in connection with the student protests over the Aghajari death sentence.

The deputy Interior Minister, Ibrahimi Rezaibabadi, said that more arrests were expected, beyond the six already confirmed at that time.

The arrests have caused anger and dismay in student and reformist circles, raising fears of further unrest just as things were apparently starting to quieten down.

	CONSERVATIVES: Leader: Supreme Leader Ayatollah Ali Khamenei Power: The real power in Iran. Controls the hard-line Guardians Council, which approves all laws, the judiciary and armed forces Where they stand: Committed to Islamic revolution. Opposed to any reduction in their powers and normalisation of relations with the US REFORMISTS: Leader: President Mohammed Khatami Power: Control the parliament and enjoy widespread popular support Where they stand: Back greater democracy, reducing the power of the Guardians Council, and reform to the legal system Iran: Who holds the power?

In response to official orders, the students had already called off their protest gatherings, which had been held on-campus, not on the streets, and in that respect were within the law.

Some have already called on the reformist President, Mohammad Khatami, to take up the case.

The student movement had already been severely weakened by the arrest and jailing of some of its key leaders, but was showing signs of being stirred into action by the Aghajari case.

As for Mr Aghajari himself, his fate remains uncertain.

Despite an intervention by the Supreme Leader, Ayatollah Khamenei, ordering a review of the verdict, the judiciary has apparently taken no concrete steps in that direction.

The Chief Prosecutor, Abdannabi Namazi, has said that there will only be a review, if Aghajari lodges an appeal, otherwise the verdict would be final.

The convicted man, a handicapped war veteran, is refusing to appeal, though he still has nearly a week to do so.

His lawyer, Saleh Nikbakht, says that there are legal ways by which the sentence could be quashed without an appeal being made, but the chief prosecutor disagrees.

In essence, it is a trial of wills between the reformists, of whom Mr Aghajari is one, and the hardliners, who control the judiciary - with a human life as the stake.