Authorities in India have arrested three people in connection with the gang-rape and hanging of two young girls in the northern state of Uttar Pradesh which sparked nationwide outraged.

The two cousins, aged 14 and 15, were found hanging from a mango tree on Wednesday morning, with subsequent tests showing that they had been victims of multiple sexual assaults.

Police on Friday said that three people, including a police constable, had been arrested following the crime in the village of Budaun.

However, Mukul Goel, a senior police officer, told the AFP news agency that it had still not been determined whether the victims had committed suicide or been strung up as a way of silencing them after they were raped.

"Only a thorough police probe would confirm whether the girls were murdered or they committed suicide," the officer told AFP.

The incident, however, has sent shock waves across the country with students and women's rights activists taking to the streets in several cities.

In capital New Delhi, protesters chanted slogans, seeking an end to the "rape culture" and demanding the resignation of the government in Uttar Pradesh government.

Rights activists and politicians said that the case highlighted that the authorities in Uttar Pradesh were "not serious" about tackling sexual crimes.

India revised its laws on sex attacks in the wake of the December 2012 gang-rape of a student on a bus in New Delhi, but tougher laws have failed to act as a deterrent.

Maneka Gandhi, the country's new federal child welfare minister, said that every officer who had been involved in the case should be dismissed.

"Police (are) still not acting in the right direction. All policemen involved in the incident should be terminated," she told the Press Trust of India (PTI) news agency, adding that she planned to set up a "rape crisis cell".

'Boys make mistakes'

Her comments came after police said that the mother of another rape victim was allegedly beaten by the father of the accused after her family refused to withdraw allegations against his son, police said Friday.

The mother, who cannot be named for legal reasons, was critically ill in hospital after suffering multiple fractures, police and medics said.

The father of the accused has been arrested and police said they were still looking for several other suspects accused of taking part in the attack on the victim's mother on May 26.

The two incidents have been seized upon by opponents of the local government in Uttar Pradesh which is run by the socialist Samajwadi Party.

The party's leader Mulayam Singh Yadav - whose son Akhilesh is the chief minister of Uttar Pradesh - told an election rally last month that he was opposed to the death penalty for gang rapists, saying "boys make mistakes".

When a reporter asked on Friday about the lawlessness in Uttar Pradesh, Akhilesh Yadav retorted: "You haven't been harmed, have you? No, right? Great. Thank you."

But he later termed the attack "unfortunate" and called for fast-track courts for speedy justice.