Indian police on Tuesday accused foreign human rights groups and Muslim organisations of inciting caste tensions after widespread protests against their handling of a gang-rape and murder of a young Dalit woman.
The assault last month of an "untouchable" Dalit teenager has sparked outrage across the country against rampant sexual violence, as well as the treatment of lower castes.
Four upper-caste men have been accused of gang rape and murder, and face the death sentence if found guilty.
But police have been accused of poorly managing the investigation and criticised for cremating the victim's body without permission.
Officers surrounded the victim's home village in Uttar Pradesh after she died, and barred anyone from meeting bereaved relatives.
They were accused of intimidating the family and attempting a cover-up in case it snowballed into a political challenge to the ruling Bharatiya Janata Party, which is in power in the state and nationally.
Police said the protests were coordinated by "anti-national" elements.
"We have reports that some foreign human rights groups, Muslim groups... are involved," a senior Uttar Pradesh police officer added.
The officer told AFP around 500 people, including six who were arrested, had been "booked" for sedition and conspiracy in recent days.
In India a booking may not necessarily lead to a formal charge, but is an incident that is officially recorded.
As fury about the case spread, another young Dalit woman died after being gang-raped in the same state.
Two men have been arrested over that attack.
More than 200 million "untouchable" Dalits in India suffer routine discrimination and violence at the hands of upper-caste communities under the rigid Hindu caste system.
The latest incidents come months after four men were hanged for the 2012 rape and murder of a student on a bus in New Delhi in a case that drew global attention towards India's problems with sexual violence.
On Monday, the United Nations in India issued a statement expressing concern about sexual violence in the South Asian nation, saying women and girls from disadvantaged social groups were at "greater risk".
India's foreign ministry called the comments "unwarranted" and said the country had a "time-tested record of providing justice to all sections of the society".