Iran's judiciary chief has tasked his deputy with leading a probe into several acid attacks on women that have sown fear across the Islamic republic and provoked rare protests in cities.
At least four women had acid hurled at them earlier this month. According to reports on social media, the victims were targeted on the face and body because they were not properly veiled, but Iranian authorities have denied that.
It is an inhuman act, unlawful, violent and anti-Islamic. Everyone must help to arrest those responsible
President Hassan Rouhani addressed the issue in a meeting with his ministers on Sunday evening, Iranian media reported.
"People should be in no doubt that the government is doing everything to arrest those responsible for these crimes," he said.
"The most severe punishment awaits them."
The attacks in Isfahan, Iran's third largest city and a top tourist attraction, drove more than 1,000 people to the streets last Wednesday to demand better security.
There were also two smaller protests in Tehran last week.
Judiciary chief, Ayatollah Sadeq Larijani, has appointed his deputy, Gholamhossein Mohseni-Ejeie, to lead the investigation.
"It is an inhuman act, unlawful, violent and anti-Islamic. Everyone must help to arrest those responsible," Mohseni-Ejeie, who will have power to oversee the justice and police authorities in Isfahan, said according to the AFP news agency.
According to justice officials, the last acid attack in Isfahan happened on October 15.
There has been little progress in finding the attackers. Several men who had been arrested were released due to insufficient evidence.
Under Islamic law, in force in Iran since the 1979 revolution, women must wear loose clothing, known as a hijab, that covers the head and neck and which conceals their hair.
But many women now push the boundaries by wearing a headscarf and thin coat rather than the chador, a traditional garment that covers the body from head to toe.