There has been a spate of acid attacks on young women in Isfahan, Iran.

According to police, attackers riding on motorbikes have thrown acid in at least four women’s faces in the city, but local media have put the number as high as eight.

There are fears that the victims were chosen because they were wearing clothing or headscarves that were revealing or did not conform to perceived Islamic norms, though authorities have so far denied that the assaults had anything to do with the hijab.

The Isna news agency has spoken to a number of victims and their families, including a 27-year-old woman, identified only by her first name Neda, who was targeted two weeks ago in Isfahan close to Bozorgmehr Square. She has since been taken to a hospital in the Iranian capital, Tehran, for further treatment but the agency said she had lost full sight in one of her eyes and has partial sight in the other.

“While in her car, Neda had pulled over in order to answer her mum’s call,” the victim’s father told Isna. “Two men riding a motorbike threw acid in her face and ran away, leaving her burnt in different areas such as her eyes, her left ear, neck, hands and legs.”

“What was her fault?” he asked. “She had not committed a single crime, she had always lived with her head kept high and never had a spat with anyone.”

Another victim, named Maryam, was also driving outside with her windows pulled down when a similar assault took place. “A rider threw nearly two litres of acid through the driver’s window towards me, which affected my face, hands and my body,” Maryam told Isna. “I did not know about the serial acid attacks in Isfahan, I think I was one of the early victims.”

Women in Iran are required by law to cover themselves head to toe but many, especially young women in bigger cities, defy the regulations and the morality police by showing their hair or wearing clothing that could be deemed inappropriate.

In public places such as big squares or universities, Iranian police caution women with “bad hijab” and sometimes arrest those who have gone too far with challenging the official line.

Despite this, the authorities have condemned the attacks in Isfahan as reprehensible, vowing to bring those responsible to justice, though they reject any link between the crimes.

“The acid attacks in Isfahan were not serial crimes,” Isna quoted the deputy interior minister, Morteza Mirbagheri, on Monday, as saying. “We have arrested three to four suspects.”

Mirbagheri said there were no safety concerns about Isfahan in regards to acid attacks and promised that the local government would fight such “insane” actions.

A member of the Iranian parliament’s national security committee, Abbas-Ali Mansouri, said: “Foreign and Zionist intelligence agencies” were aiding those carrying out the attacks in order to distort Islam’s image worldwide.

The attacks have led to widespread panic and nervousness in Isfahan, the reformist Shargh daily reported. “The news about the acid attacks have attracted a great deal of attention the on internet and have prompted fear among women,” the newspaper said.

Local news sites have asked why all the victims have been young women.

Acid attacks in Iran are usually linked to personal grudges. In 2011, the case of an Iranian woman who was blinded when a spurned suitor threw acid at her drew international attention.