India strongly rejected Canada's charges of its agents' involvement in Nijjar's killing.
India on Sunday night described as "fake" and "completely fabricated" a media report which claimed that a "secret memo" was issued by New Delhi in April to take "concrete" measures against certain Sikh separatists including Hardeep Singh Nijjar.
External Affairs Ministry spokesperson Arindam Bagchi said the report is part of a "sustained disinformation campaign" against India and the outlet that came out with it is known for propagating "fake narratives" peddled by Pakistani intelligence.
Online American media outlet The Intercept came out with the report.
"We strongly assert that such reports are fake and completely fabricated. There is no such memo," Mr Bagchi said.
"This is part of a sustained disinformation campaign against India. The outlet in question is known for propagating fake narratives peddled by Pakistani intelligence. The posts of the authors confirm this linkage," he said.
"Those who amplify such fake news only do so at the cost of their own credibility," he said, responding to media queries on the report.
In September, Canadian Prime Minister Justin Trudeau made the allegation of a "potential" involvement of Indian agents in the killing of Nijjar on Canadian soil on June 18.
India strongly rejected the charges, calling them "absurd".
In its report, The Intercept claimed that the Indian government issued instructions on a "crackdown scheme" against certain Sikh entities in western countries.
It further claimed that the secret memorandum issued in April by the Ministry of External Affairs lists several "Sikh dissidents under investigation by India's intelligence agencies, including the Canadian citizen Hardeep Singh Nijjar".
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)