Iran's supreme leader Ayatollah Ali Khamenei appealed for calm in a bid to defuse unprecedented political tension in the Islamic regime following the shock resignation of a top religious leader and anti-clerical attacks. State radio repeatedly broadcast the text of a letter Khamenei wrote to Ayatollah Jalaledin Taheri, prayer leader in the central city of Isfahan, accepting his resignation and taking on board some of the strong criticism of the regime which accompanied it. (Read photo caption)

"Without doubt, one of the objectives of our enemies is to provoke clashes among the population, which is why I ask the population in Isfahan to maintain their calm and avoid any slogans and actions during the Friday prayer ceremony," Khamenei said in his message broadcast ahead of weekly prayer ceremonies nation-wide Friday.

Taheri's resignation Tuesday came with a fiery attack on the Islamic state and its dominant conservative religious leaders, who accept no authority but Khamenei's and through control of the judiciary and other key bodies constantly hamper reform attempts by backers of moderate President Mohammad Khatami.

It listed "deception, unemployment, inflation, the diabolical gap between the rich and poor, bribery, cheating, growing drug consumption, the incompetence of authorities and the failure of the political structure" of the regime as reasons for him stepping down.

His unprecedented criticism prompted the Supreme National Security Council (SNSC) to bar the press from reporting "in favour of or against" Taheri.

Khamenei said the resignation came "unexpectedly," but added that he agreed with Taheri "because I also have been saying for several years that we have to mobilize all possible means to fight poverty and corruption."

He went on to suggest "solutions" to some of the problems listed by Taheri in his letter, including the "production and creation of jobs, notably for the young, a harmonious fight against economic corruption, notably in state bodies," as a way out of the current crisis.

But Khamenei also warned that the current "circumstances" require that officials pay attention to what they say "because any unjust criticism encourages enemies and counter-revolutionaries who benefit from the support of the United States and Israel."

"The United States has realised its threats against the regime and wants to have a solid base inside (the country) in order to avenge the revolution and establish a black dictatorship like that in the former regime" of the shah, he said.

But Khamenei added, "The people back the revolution and the regime."

He also justified measures taken against dissident religious leader Hossein Ali Montazeri, who was chosen by the Islamic regime's founder, Ayatollah Ruhollah Khomeini, to succeed him but fell into disgrace, enabling Khamenei to become supreme leader in his place.

Taheri, 76, also a former close associate of Khomeini, had raised the fate of Montazeri, who has been under house arrest in the city of Qom, in his resignation letter.

Taheri's bombshell coincided with the anniversary of the July 1999 student unrest, which saw thousands of people defy a government ban Tuesday and take to the streets of Tehran and other cities.

PHOTO CAPTION

Reformist Iranian President Mohammad Khatami, left, accompanied by Ayatollah Jalaleddin Taheri, who led Friday prayers in central Isfahan for 30 years, is shown in this November 1999 file photo. Iran's largest reform party and more than 100 lawmakers have come out in support of the popular cleric who resigned in protest over the hard-line authorities, reports said Thursday, July 11, 2002.(AP Photo/Hasan Sarbakhshia