Four sisters walking home in north India have suffered severe burns after being attacked with acid by two men on a motorbike, police said Wednesday, in a brutal example of a growing problem in South Asia.
The youngest sister, a 19-year-old student, was admitted to hospital after the attack on Tuesday evening in the Shamli district of Uttar Pradesh state, about 100 kilometres (60 miles) from the capital.
"The victims were walking together when two men on a motorbike made lewd remarks and the man who was riding pillion splashed acid on all of them," Abdul Hameed, the senior police officer investigating the case, told AFP.
"The youngest sister suffered maximum burn injuries and she had to be rushed to a hospital in Delhi."
Hameed said no arrests had been made and the motive behind the crime was being investigated, with other family members set to be questioned to identify possible suspects.
The three other sisters were all teachers at a local government school and were returning home from work. They were taken to hospital for treatment but not admitted.
Attacks on women have topped the national agenda since December, when a medical student was assaulted and raped by six men on a moving bus in Delhi. She died two weeks later of her injuries.
Public anger prompted parliament to toughen sex offence laws including doubling the minimum prison sentence for gang-rape to 20 years, but lawmakers voted against increasing the punishment for acid attackers.
They can be jailed for eight to 12 years depending on the injuries inflicted, but the offence is bailable.
The incident prompted senior police officers in the state of Uttar Pradesh to meet. They decided to ask shopkeepers to register the name and address of people buying acid, said senior state officer Atul Saxena.
"We have no powers to stop the sale of acid. It is for the local government to curb the availability of the dangerous chemical," he told AFP.
Campaign group Stop Acid Attacks has accused the federal government of ignoring the growing trend of such assaults, which are often perpetrated by jilted boyfriends or their relatives.
It has called for India to regulate the sale of an acid called "Tezaab" which is designed to clean rusted tools but is commonly used in attacks.
"Acid has become the cheapest and most effective tool for men to attack women in India," said activist and victim Archana Kumari, who hails from northern Uttar Pradesh state where Tuesday's attack took place.
"Why is the government not stopping the sale of acid? Why are they supporting a weapon that has the power to kill and ruin a woman's life?" she said.
The country's top court in February ordered the federal government to find ways to curb the sale of acid, and draft a new set of laws that promise compensation and medical aid to the victims of acid attack.
According to the London-based charity Acid Survivors Trust International, about 1,500 acid attacks are reported globally each year.
But many more victims do not report their injuries to the authorities and instead suffer in silence.
In 2011 neighbouring Pakistan adopted legislation increasing the punishment to between 14 years and life for acid attacks and a minimum fine of one million Pakistan rupees ($10,200).