Christian Solidarity Worldwide is urging India to address sexual violence following the gang rape and murder of a 23-year-old student in Delhi last month.
There have been widespread protests in India following the attack, which shocked the nation and led to calls for an end to violence against women.
CSW said that sexual violence was "endemic" within the context of communal violence against minorities.
A nun was gang-raped in the Kandhamal violence in Orissa state in 2008. In an unprecedented move, she spoke publicly about her ordeal in a press conference, revealing that she had been raped by a gang of men and paraded half-naked down the street.
She told of how she appealed to the police to help her but they did nothing and she was dragged away again by the mob. CSW reports that, four years on, the nun has still not received justice.
More recently, two 13-year-old girls were raped last October as they returned home from celebrating the Hindu Dussehra festival. One girl died in the attack, while the other was dismissed by the Orissa State Commission for the Protection of Child Rights and the officer-in-charge at a special all-female police station.
There have been delays to draft legislation aimed at addressing communal and targeted violence, including sexual assault.
In India's Universal Periodic Review at the UN last year, Germany pressed for the introduction of communal and targeted violence bill.
CSW's South Asia Team Leader, David Griffiths, said, "Many human rights activists and ordinary citizens in India are looking to their government for a healthy policy response to the Delhi rape tragedy.
"We have continued to urge the government to introduce legislation dealing with the specific contingencies of communal and targeted violence, which include sexual violence.
"Over the years, rape has often been used as a weapon to spread fear and humiliate the community being targeted for violence, and many victims remain deeply scarred and have had little or no justice.
"We wish to express our profound concern and solidarity with them, and urge the government to act swiftly on their behalf at a time when the horror of rape and sexual violence is very much on the national agenda."