Iran has arrested eight people, including a leading model, for what it calls "un-Islamic" acts online such as posting photos of themselves without their hair covered.

According to state media, the crackdown is part of an operation code-named Spider II, and is particularly aimed at those who share images of themselves on Instagram and other social media sites.

A television report included footage of Iranian model Elham Arab speaking before Tehran prosecutor Abbas Jafari Dowlatabadi in a conference room.

Arab, who is well-known for modelling wedding dresses and posting pictures of herself without a headscarf, said: "All people love beauty and fame.

"They would like to be seen, but it is important to know what price they will pay to be seen."

The report did not say what charges she faced, nor did it identify the other seven people arrested but they are among 170 people police are investigating.

It is believed most of them work mainly in the fashion industry and include makeup artists, photographers and designers, many of whom have had their businesses shut down as a result.

Mr Dowlatabadi has been quoted by the state-owned Iran newspaper as saying "we must fight with enemy's actions in this area, of course our actions in this area will continue".

Crackdown

The arrests are said to show that hard-liners in the police and judiciary still hold significant power in the country despite President Hassan Rouhani having a reputation as a moderate.

In recent years, Iranian women, especially in the capital Tehran, have worn the mandatory scarf loosely on their heads, which has angered conservatives.

Tehran's police chief General Hossein Sajedinia announced in April that 7,000 male and female officers would go undercover to enforce the government-mandated Islamic dress code.

The crackdown on the fashion industry is part of a broader emphasis to control online expression in the county.

Nearly 40% of Iran's 80 million people can access the internet, although the American-based watchdog Freedom House describes web access as "not free" due to censorship and filtering.

In May 2014, authorities arrested a group of young Iranian men and women for an online video of them dancing to Pharrell Williams' song Happy.

Even though the arrests drew widespread criticism, including from the musician himself, those involved were each given suspended sentences of six months' in prison and 91 lashes.

Journalists, filmmakers, writers and activists have also been detained, sentenced or imprisoned.

Photo-sharing site Instagram, which is owned by Facebook, has not yet commented.