Both reformists and Conservatives have been holding angry demonstrations. What has provoked them?

Student rallies were called to protest against the death sentence passed in early November on Hashem Aghajari, a liberal university lecturer convicted of apostasy for an address he made last June critical of the role of the Islamic clergy.

The protests were relatively small - around a few thousand people - and confined to speeches and slogan shouting on university campuses, not the streets.

Much bigger, officially-encouraged and organised demonstrations have also taken place in public, usually to mark certain occasions, and have often involved the chanting of anti-reformist and anti-student slogans, as those taking part are generally hardliners.

Why has the death sentence been passed on Aghajari? What are the key issues at the centre of this case?

His remark that Muslims should not uncritically follow the line laid down by their clerical leaders "like monkeys" enraged hardliners, some of whom said Aghajari was worse than the author Salman Rushdie and should be put to death.

The judge ruled that Aghajari was guilty of apostasy, which automatically carries the death penalty.

Issues at stake include, for reformists: the freedom of speech and opinion; and the right to an open trial before a jury, guaranteed in the constitution.

For conservatives: the necessity to safeguard the sanctities of Islam from attacks they regard as blasphemous.

Parliament recently backed reformist President Khatami in a bill that would allow him to suspend rulings by the conservative judiciary. Will this bill become law, or do the conservatives have the power to block these reforms?

This bill and another one which would curb the powers of the conservative Council of Guardians are expected to pass easily through the reformist-dominated parliament.

But the Council of Guardians itself has to approve them, and that is thought highly unlikely.

If there is a standoff, the bills may pass to an arbitrating body, the Expediency Council, and at that point the position taken by the country's Supreme Leader, Ayatollah Ali Khamenei, may become crucial.

There will be strong pressure on reformist leaders such as President Khatami, who sponsored the bills, to resign if they are not passed.

One way or another, the situation will be extremely critical.

Where does Iran's Supreme Leader, Ayatollah Khamenei, stand in this trial of strength between reformists and conservatives?

Generally speaking but not always, the Supreme Leader tends to come down on the side of the conservatives.

He is often portrayed as leading the hardliners, but in reality, it is more of a balancing act.

Are we approaching an all-or-nothing showdown between hardliners and reformists?

In the coming months it looks as though the Islamic Republic may be heading into a fateful period where the contradictions between the "Islamic" and "Republican" concepts have somehow to be reconciled.

Time is running out for the reformists, who, despite their electoral successes have little to show for their years in office because their efforts have been blocked by the entrenched hardline minority.

However, the Islamic regime has often shown an ability to produce, at the last minute, just enough elasticity to keep going.

Is violence likely if demonstrations continue?

So far, the protests have been largely confined to university campuses, where security forces are not allowed to intrude.

There have been some limited skirmishes on-campus with hardline student or basij (Islamic volunteer) elements. These protest gatherings have recently been suspended under official orders.

If demonstrations, perhaps over the latest wave of student arrests, should spill onto the streets and persist, it is highly likely that violence will ensue, since they are illegal unless covered by a prior permit - which is rarely forthcoming.