The papers, Kayhan and Javan, were accused by the Presidential office of violating the press code by printing a confidential letter.

The letter from 24 senior Revolutionary Guard commanders accused the president of leading the Islamic Republic into "anarchy" and blamed him for the student protests.

It was seen by supporters of President Khatami as a warning of possible military intervention or coup.

"How long do we have to be subjected to this trial run of democracy, which has turned into anarchy and puts the Islamic regime at risk?" the letter said.

Newspapers closed

Two weeks ago, the authorities closed down a liberal newspaper, Salam, for allegedly publishing a secret letter. The move was seen as part of crackdown by Iranian hardliners against liberal newspapers which have flourished under the moderate reformist president.

Supporters of Mr Khatami have now urged the conservative-dominated judiciary to prove its impartiality by taking action against the two papers.

Correspondents say any firm action against Kayhan in particular is bound to have far-reaching implications, as its director is appointed by the Iranian supreme leader, Ayatollah Ali Khamenei.

On Friday the head the Revolutionary Guards, Rahim Safavi, reaffirmed official support for President Khatami saying that the guards had "always supported the president and will not tolerate attempts to weaken or insult him".

BBC's Jim Muir: The president was clearly angered by the criticism

Referring to the letter, General Safavi said the well equipped Revolutionary Guards, who are under the command of Ayatollah Khamenei, are responsible for supporting the president "as a pillar of the present political system in Iran".

Student accusations

Last week Iranian student leaders warned that future generations would turn to non-peaceful means to achieve reform if hardline conservatives continue to block the programmes of President Mohammad Khatami.

Students say members signed confessions while blindfolded

The students have accused the Iranian security forces of beating and torturing members who were arrested during last week's protests and say they are continuing to round-up and arrest pro-democracy activists.

The authorities say most of the 1,400 people who were arrested have been freed.

But the Council for Student Protesters, a student committee set up after the incidents, said that some of its own members, as well as other students, were still being detained.