The number of women defying the dress code that headscarves must be worn in public has increased since a protest movement triggered by the death in custody last year of Kurdish-Iranian Mahsa Amini, 22, for allegedly flouting it.

A statement on the police website on Saturday said action would be taken “from today” over violations in public places, in cars and other “sites where hijab is sometimes removed”.

“In this context, technology will be used for the smart identification of people who break the law,” it said.

“Removing hijab is considered a crime, and the police deal with social anomalies within the framework of the law,” the statement quoted Security Police chief Hassan Mofakhami as saying.

“People who break the law are responsible for their actions and should be held accountable for their behaviour,” he added.

A wave of civil protest swept the Islamic republic after Amini’s death last September 16, three days after her arrest by the morality police.

Thousands of people were arrested, hundreds killed – including members of the security forces – and four people executed because of the civil unrest following Amini’s death, with Iran labelling the protests as foreign-instigated “riots”.

Mofakhami also warned that businesses whose employees removed their headscarves in the workplace faced closure.

He said in such cases a warning would be issued, but “if the warning is repeated, the closure of the business will be on the agenda”.

Last week, police chief Ahmad-Reza Radan said those who remove their headscarves would be identified using “smart equipment”.

“People who remove their hijab in public places will be warned first and presented to the courts as a next step,” he said.

Car owners would also receive a warning text if any passengers violated the dress code, and their vehicles would be seized if the offence was repeated.

In late March, the head of the judiciary, Gholamhossein Mohseni Ejei, said “removing hijab amounts to enmity towards values and people who commit such abnormality will be punished”.

The requirement for women to wear the headscarf in public was enshrined in law shortly after the Islamic revolution of 1979.