Iranian authorities, irked by the scale of public outrage about a string of acid attacks in the city of Isfahan, have turned on the media that brought the horrific incidents to the country’s attention.

The semi-official Isna news agency, one of the first Iranian media organisations to probe the assaults and interview victims, has come under attack from hardliners who have criticised the coverage of the vicious assaults in domestic and foreign news websites.

At least four Isna staff members in Isfahan were detained on Monday. Two were released after brief detentions but the remaining journalists remain in custody. They have been identified as Zahra Mohammadi, the head of Isna’s office in Isfahan, and Sanam Farsi, its social affairs editor.

Assailants riding on motorbikes have thrown acid in the face of at least eight women driving with their windows down. Iranians are horrified about the assaults, which have sparked protests in Isfahan and Tehran. Many believe the victims were chosen because of the way they dressed, but the authorities have denied this.

Iranian officials are particularly angry with any suggestion that attackers were driven by religious extremism, or that victims were targeted because they wore clothing that could be deemed inappropriate in the eyes of hardliners. But despite the state’s condemnation of the Isfahan incidents, many in Iran believe that a long-standing strict policy on women’s clothing has encouraged such attacks.

Women in Iran are required by law to be covered from head to toe, but many defy the regulations by revealing their hair.

It also emerged over the weekend that Isna’s local photographer, Arya Jafari, who documented last week’s public protests in Isfahan, had been detained and was in custody. Jafari’s pictures of the protest were initially published as a photo gallery by Isna and were later distributed worldwide through AFP and Getty Images.

Jason Stern from the New-York-based Committee to Protect Journalists (CPJ) condemned the arrests. “This case deals with everything Iranian hardliners can’t stand: critical media coverage, street protests, women’s rights and government accountability,” he told the Guardian.

“So they have turned yet again to their tired practice of arresting journalists in a failed attempt to prevent Iranians and the world from knowing what is really happening in Isfahan. All of the arrested journalists should be released immediately.”

In recent days, a number of Iranian officials have stepped up their rhetoric against the media because of their coverage of the attacks.

Iran’s prosecutor general, Ibrahim Raeesi, was quoted as saying that a group of news agencies had made accusations that were untrue. He denied that the acid attacks were linked in any way to the state’s policing of morality.

Sadeq Larijani, the head of the Iranian judiciary, also spoke against media organisations that he said “polluted the atmosphere”. On Tuesday, Hassan Firouzabadi, the chief of staff of the Iranian armed forces, said the impact of some media reports was “worse than acid attacks”.

Iranian authorities, panicking about the public sense of outrage and fear, have given conflicting accounts about the incidents and their aftermath. The governor of Isfahan’s province, Rasoul Zargarpour, is the latest figure to comment on the number of suspects arrested. “So far, 10 suspects have been identified with respect to acid attacks in the province, who are being interrogated by the police,” he said on Monday, according to the state-run Press TV.