Iran has arrested dozens of people, including Instagram models and beauty salon owners, for posting photos online, in the latest crackdown against “immoral” behaviour.

More than 40 people, including at least eight women, have been rounded up in the southern port city of Bandar Abbas, 630 miles south of Tehran, according the official IRNA news agency.

Among the detainees are Instagram models, and people who work in photography, beauty salons and wedding businesses, who used social media to share footage that the state deems “indecent”.

Police said those arrested were “damaging public virtue through the organised spreading of anticultural” activities.

Earlier this month the authorities arrested Maedeh Hojabri, an 18-year-old Instagram star who had attracted 88,000 followers for her dance videos. She appears in at least 300 posts and in many is dancing to both Iranian and western pop music in clothes that violate Iran’s strict Islamic dress code. In others, she wears the mandatory Islamic headscarf.

Local media reported she has been released on bail, and is not thought to be among those arrested this week.

State TV broadcast a “confession” by the teenage gymnast, in which she insisted she was not trying to break moral norms but only secure more followers. It was unclear if the statement was made under duress.

However, her detention sparked anger in Iran, where women began posting photos of themselves dancing to show solidarity, along with the hashtag “dancing is not a crime”.

At the time Iranian police vowed to crack down further, and said they planned to shut down similar accounts on the popular social media network. The judiciary said it was considering blocking access to the site.

Since the 1979 Iranian Revolution, the country has had strict rules governing women’s behaviour and dress. Women can face penalties ranging from a $25 (£19) fine to prison time for even showing their hair.

Earlier this year dozens of women were arrested for joining peaceful protests against compulsory veiling. Many of them posted videos of themselves removing their headscarves in public and holding them aloft.

In February, Amnesty International reported that Iranian police had warned that women who joined the protests faced up to a decade in jail on charges of “inciting corruption and prostitution”. The rights group said the authorities were holding some of the women in solitary confinement.