"The victims of the 1984 massacres have waited for the law to take its course and, sadly, they are still waiting. The Government should prosecute those involved in the riots," Meenakshi Ganguly, senior researcher on South Asia at Human Rights Watch (HRW), said.
"Both the militants and the security forces committed horrific crimes, justifying them by pointing to the abuses of the other, and yet those who suffered most were ordinary civilians," she added.
Two decades after the incident, victims and their families seeking justice "have been confronted by government opposition and obfuscation, including prolonged trials, biased prosecutors, an unresponsive judiciary, police intimidation, and harassment of witnesses," a HRW statement noted.
It further alleged that no senior government officials or politicians have been prosecuted despite evidences of their role in the atrocities.
Numerous commissions of inquiry, each with the promise of justice, have produced no tangible results, it added.
Widespread killing of Sikhs by violent mobs were triggered after the assassination of Prime Minister Indira Gandhi by two of her Sikh bodyguards.