The UN freedom of religion investigator has warned that India risks more religious violence, like Gujarat's 2002 riots that killed 2,500 people, as delays to bring justice encouraged an atmosphere of impunity.
"All these incidents continue to haunt the people affected by them and impunity emboldens forces of intolerance," Asma Jahangir told a news conference as she finished off a tour of India at the end of last week.
"Today there is a real risk that similar communal violence might happen again unless incitement to religious hatred and political exploitation of communal tensions are effectively prevented," said Jahangir, who is a Pakistani rights activist.
India's constitution is secular. Hindus account for 80 percent of India's billion-plus population, while Muslims account for about 13 percent, Christians less than 3 percent and minorities such as Sikhs, Buddhists, Jains and Parsis the rest.
Over the past two decades, India has suffered major religious riots between its different communities, like in the western state of Gujarat in 2002 when mainly Muslims were massacred by Hindu nationalists.
"Even today there is increasing ghettoization and isolation of Muslims in certain areas," she said, referring to Gujarat state run by controversial Hindu nationalist Narendra Modi.
But many of the perpetuators of religious riots have never been jailed amid a slow judicial system and what critics say is government inertia.
Jahangir criticised the slowness of government inquiries into previous religious clashes.
She said she was "astonished" that one government commission probing the demolition of a 16th century mosque in the northern Indian town of Ayodhya had received a 44th deadline extension.
The demolition of the mosque by Hindu nationalists sparked the 1993 bombings in Mumbai which killed 257 people. Those attacks were blamed on Muslim gangsters.
Jahangir criticsed law enforcement authorities for being reluctant to act against perpetuators of religious violence.
"At the same time, organised groups based on religious ideologies have unleashed the fear of mob violence in many parts of the country," she said.
"This institutionalised impunity for those who exploit religion and impose their religious intolerance on others has made peaceful citizens, particularly the minorities, vulnerable and fearful."
Jahangir, known as the United Nations Special Rapporteur on freedom of religion, highlighted attacks on Indians marrying people from different castes and religions in northern India, and attacks on Christians, lower castes and tribal people in the eastern state of Orissa last year.
In Orissa, where many churches were attacked around Christmas last year, she said there were credible reports that members of the Christian community had alerted authorities in advance.
