The official spoke on condition of anonymity as they were not authorised to speak publicly ahead of public reaction from the Canadian government later Tuesday. The official confirmed an earlier report from the Financial Times.
India’s Ministry of External Affairs declined to comment.
Arranging the killing of a Canadian citizen in Canada, home to nearly 2 million people of Indian descent, would be unprecedented.
India has accused Canada for years of giving free rein to Sikh separatists, including Nijjar.
India has also cancelled visas for Canadians. Canada has not retaliated for that. India also previously expelled a senior Canadian diplomat after Canada expelled a senior Indian diplomat.
The allegation of India’s involvement in the killing is based in part on the surveillance of Indian diplomats in Canada, including intelligence provided by a major ally, a separate Canadian official previously told Associated Press.
The official said the communications involved Indian officials and Indian diplomats in Canada and that some of the intelligence was provided by a member of the “Five Eyes” intelligence-sharing alliance, which includes the United States, Britain, Australia and New Zealand, in addition to Canada. The official spoke on condition of anonymity because of not being authorised to discuss the matter publicly.
Nijjar, a plumber, was also a leader in what remains of a once-strong movement to create an independent Sikh homeland, known as Khalistan. A bloody decade long Sikh insurgency shook north India in the 1970s and 1980s, until it was crushed in a government crackdown in which thousands of people were killed, including prominent Sikh leaders.
The Khalistan movement has lost much of its political power but still has supporters in the Indian state of Punjab, as well as in the sizeable overseas Sikh diaspora. While the active insurgency ended years ago, the Indian government has warned repeatedly that Sikh separatists were trying to make a comeback.