Eight people were arrested in Iran last week for what Tehran's cybercrimes court prosecutor calls "un-Islamic" Instagram modeling.

"Sterilising popular cyberspaces is on our agenda," said Mostafa Alizadeh, spokesman of the Iranian Centre for Surveying and Combating Organized Cyber Crimes, according to the BBC. "We carried out this plan in 2013 with Facebook, and now Instagram is the focus," he added.

The arrests were part of a two-year-old operation called Spider II, which targets women posting photos of themselves showing their hair or not wearing headscarves on social media. So far, investigators have identified more than 170 popular Iranian Instagram accounts of women involved in modeling, makeup, and hairstyling, and opened criminal cases against 21 users, in addition to the eight women arrested.

The recent crackdown highlights hardliners' continued power and commitment to implementing a strict interpretation of Islamic law, squashing the hope for reform at home that rose after the nuclear deal was signed last summer, when many Iranians looked forward to the prospect of re-engaging with the West and an improved economy.

Tehran police chief Gen. Hossein Sajedinia in April announced his department had deployed 7,000 male and female officers for a new plainclothes division — the largest such undercover assignment in memory — to enforce the government-mandated Islamic dress code, the Associated Press reported.

Fundamentalist officials, however, still aim to protect the Islamic cultural purity of Iran against the West's "cultural invasion."

Since 1979, women have been required by law to cover their hair in public. In recent years, however, especially in Tehran, women have begun to wear the headscarf more loosely, showing a bit of hair and inciting conservatives.

Court prosecutor Javad Babaei defended the arrests, saying that social media poses "threats to morality and the foundation of family," as the BBC reported. Mr. Babaei said that the modeling agencies make and spread "immoral and un-Islamic culture and promiscuity," adding that the agencies account for 20 percent of the country's Instagram posts.

Among the 29 who received legal notice, 21 "reformed their behavior," Babaei said. The other eight were arrested.

About 40 percent of the Iran's 80 million people have Internet access, but it is subject to censorship and filtering, according to Freedom House, a US-based nonprofit promoting freedom and democracy, which rates the country "not free." Facebook, Twitter, and YouTube are blocked in Iran, making Instagram a popular social media alternative.

In May 2014, a group of six young Iranians was arrested for a video set to the Pharrell Williams pop hit "Happy," which they posted online. The video, and its immediate spinoffs, coincided with "a separate new Internet phenomenon, in which Iranian women post photographs of themselves outdoors but unseen, joyfully casting off their headscarves," as the Monitor's Scott Peterson reported at the time.

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Iranian officials told journalists that the social media crackdown would continue.

"We must fight with enemy's actions in this area," said Tehran prosecutor Abbas Jafari Dowlatabadi, according to state-owned IRAN newspaper. "Of course our actions in this area will continue."