TRENTON, Canada

There are “credible allegations” that the government of India was behind the shooting death of Sikh leader Hardeep Singh Nijjar in Surrey, British Columbia (B.C.), Canadian Prime Minister Justin Trudeau said Monday.

Nijjar, a Sikh leader in the western Canadian province of B.C., was shot to death on June 18 in front of a Sikh temple in the city of Surrey. No arrests have been made.

"Over the past number of weeks, 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, addressing the House of Commons after he spoke with opposition political party leaders.

Nijjar, a Canadian citizen, was a vocal supporter of independence for the Khalistani state in the Punjab region. The Indian government has repeatedly insisted Nijjar was a terrorist – a label his supporters denied – and at the recent G20 summit in New Delhi, Prime Minister Narendra Modi chided Trudeau for allowing Sikh separatist protests in Canada.

Trudeau in turn told Modi that peaceful demonstrations were permitted in democratic Canada. Monday, the prime minister had harsh words for the Indian government.

"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."

Trudeau called for India to participate in the investigation to “get to the bottom of this matter.”

Foreign Affairs Minister Melanie Joly said that Canada expelled a "top Indian diplomat" and Canada expects India's full collaboration "to get to the bottom of this."

According to the reports, the diplomat was Pavan Kumar Rai, Canadian head of New Delhi’s Research and Analysis Wing, the Indian foreign intelligence agency.

Relations with India were already strained to the point that two weeks ago, the Canadian government postponed a trade mission to India slated for Oct. 9.

There has been no reaction from India to date.