Five men have been arrested over the brutal gang-rape and murder of two girls found hanging from a mango tree in northern India, police said Saturday.

The discovery Wednesday of the bodies of the cousins, aged 14 and 12, in impoverished Katrashadatganj village in Budaun district of Uttar Pradesh, marked the latest sexual violence case to stir national outrage.

"Rape of both girls has been confirmed. Cause of death was asphyxia," Budaun district police superintendent Atul Saxena said.

Preliminary charges of murder and gang-rape were filed against three men while two policemen are accused of being criminal accessories, Saxena said.

"These men  first raped the victims and then hung them as now confirmed by post-mortem reports," Saxena said.

"The girls were still alive when they were hung," Saxena said by phone from the district, 180 miles from Uttar Pradesh capital Lucknow.

He said all those named in a police complaint by the families had been arrested and police were probing whether more were involved.

The farm family of the two cousins told Agence Ffrance-Presse that police could have "saved" the girls but said they refused to help when they found they were from a low caste.

"She was my everything, my world, and now my world has come to an end," said the grief-stricken father of one victim. The alleged attackers were from a higher caste than the girls.

There is a long history of women and girls from India's lower castes, especially those who are Dalits, previously known as "untouchables," being sexually abused by people from higher castes.

"These policemen didn't act for hours when they could have saved two young lives. Why is caste everything?" said the father, who cannot be named for legal reasons.

The victims were sexually assaulted multiple times, police said.

India toughened sex assault laws following the fatal December 2012 gang-rape of a student on a bus in New Delhi that triggered nationwide protests, but the move has done little to stem the tide of sex attacks.

According to Indian government statistics, a rape happens every 22 minutes but activists say the figure is low because many rapes go unreported in the nation of 1.2 billion people.