Prime Minister Justin Trudeau is accusing the government of India of being behind a fatal shooting on Canadian soil.

Canadian citizen Hardeep Singh Nijjar was brazenly shot dead outside a Sikh temple in Surrey, B.C. on June 18.

Nijjar, a supporter of a Sikh homeland in the form of an independent Khalistani state, had been branded by the Indian government as a "terrorist" and accused of leading a militant separatist group — something his supporters have denied.

Now, Trudeau said, Canada's national security apparatus has reason to believe that "agents of the Indian government" carried out the killing of this Canadian citizen, who also served as the president of Surrey's Guru Nanak Sikh Gurdwara.

"Canadian security agencies have been actively pursuing credible allegations of a potential link between agents of the Government of India and the killing of a Canadian citizen, Hardeep Singh Nijjar," Trudeau said Monday.

"Any involvement of a foreign government in the killing of a Canadian citizen on Canadian soil is an unacceptable violation of our sovereignty. It is contrary to the fundamental rules by which free, open, and democratic societies conduct themselves," Trudeau said.

"As you would expect, we have been working closely and coordinating with our allies on this very serious matter."