Iran's clerical rulers are clamping down on dissent ahead of the anniversary of the death of a young woman in morality police custody, fearing a revival of nationwide protests that rocked the Islamic Republic for months.

Journalists, lawyers, activists, human rights advocates and students have been arrested, summoned or faced other measures in a campaign that one activist described as "instilling fear and intimidation".

Senior officials have defended the new crackdown as necessary to maintain stability. But some politicians and insiders have said that mounting repression could deepen a crisis between the clerical leadership and society at large at a time of growing popular discontent over economic woes.

Police on Sunday announced that the morality police force has intensified its crackdown on women flouting the compulsory dress code. In a show of civil disobedience, unveiled women have frequently appeared in public since the death of 22-year-old Mahsa Amini on Sept. 16 last year.

Social media was flooded with angry comments from Iranians criticizing the return of the morality police, who had largely vanished from streets since Amini died in their custody.

Rights advocates said the state had stepped up its repression to "keep people off the streets" ahead of Amini's death anniversary.  "The Islamic Republic feels threatened.  By redeploying the morality police, the regime is fueling the people's revolution".    "People are very angry due to repression, rights violations and worsening economic problems.  All these will result in revival of street protests."