Hardeep Singh Nijjar, an advocate of Sikh independence from India, was gunned down on 18 June outside a Sikh cultural centre in the Canadian province of British Columbia.
India dismissed allegations that its government was linked to the killing of a Sikh activist in Canada as "absurd" on Tuesday, expelling a senior Canadian diplomat and accusing Canada of interfering in India's internal affairs.
It came a day after Canadian Prime Minister Justin Trudeau described what he called credible allegations that India was connected to the assassination of Hardeep Singh Nijjar, an advocate of Sikh independence from India who was gunned down on 18 June outside a Sikh cultural centre in Surrey, British Columbia, and Canada expelled a top Indian diplomat.
"Any involvement of a foreign government in the killing of a Canadian citizen on Canadian soil is an unacceptable violation of our sovereignty," Trudeau told Parliament Monday. "In the strongest possible terms, I continue to urge the government of India to cooperate with Canada to get to the bottom of this matter."
The duelling expulsions come as relations between Canada and India are tense. Trade talks have been derailed and Canada just cancelled a trade mission to India that was planned for the fall.
In its statement announcing the expulsion, India's Ministry of External Affairs wrote that "the decision reflects Government of India's growing concern at the interference of Canadian diplomats in our internal matters and their involvement in anti-India activities."
Nijjar was organising an unofficial referendum in India for an independent Sikh nation at the time of his death. Indian authorities announced a cash reward last year for information leading to Nijjar's arrest, accusing him of involvement in an alleged attack on a Hindu priest in India.
India has repeatedly accused Canada of supporting the Sikh independence, or Khalistan, movement, which is banned in India but has support in countries like Canada and the UK with sizable Sikh diaspora populations.
In March, the Modi government summoned the Canadian High Commissioner in New Delhi to complain about Sikh independence protests in Canada. In 2020, India's foreign ministry also summoned the top diplomat over comments made by Trudeau about an agricultural protest movement associated with the state of Punjab, where many Sikhs live.
Canada has a Sikh population of more than 770,000, or about 2% of its total population.
Trudeau told Parliament that he brought up Nijjar's slaying with Indian Prime Minister Narendra Modi at the G20 meeting in New Delhi last week. He said he told Modi that any Indian government involvement would be unacceptable and that he asked for cooperation in the investigation.
India's foreign ministry dismissed the allegation as "absurd and motivated."
"Such unsubstantiated allegations seek to shift the focus from Khalistani terrorists and extremists, who have been provided shelter in Canada and continue to threaten India's sovereignty and territorial integrity," it wrote in a statement issued earlier Tuesday.
At the G20 meeting, Modi expressed "strong concerns" over Canada's handling of the Punjabi independence movement among the overseas Sikhs during a meeting with Trudeau at the G20, the statement added.
The statement called on Canada to work with India on what New Delhi said is a threat to the Canadian Indian diaspora and described the Sikh movement as "promoting secessionism and inciting violence" against Indian diplomats. Earlier this year, supporters of the Khalistan movement vandalised Indian consulates in London and San Francisco.
Canadian Foreign Minister Mélanie Joly said Canada had expelled a top Indian diplomat, whom she identified as the head of Indian intelligence in Canada.
"If proven true this would be a great violation of our sovereignty and of the most basic rule of how countries deal with each other," Joly said. "As a consequence, we have expelled a top Indian diplomat."
Public Safety Minister Dominic LeBlanc said Canada's national security adviser and the head of Canada's spy service have travelled to India to meet their counterparts and to confront the Indian intelligence agencies with the allegations.
He called it an active homicide investigation led by the Royal Canadian Mounted Police.
Joly said Trudeau also raised the matter with US President Joe Biden and UK Prime Minister Rishi Sunak.
"We are deeply concerned about the allegations referenced by Prime Minister Trudeau," White House National Security Council spokesperson Adrienne Watson. "We remain in regular contact with our Canadian partners. It is critical that Canada's investigation proceed and the perpetrators be brought to justice."
Joly also said she would raise the issue with her peers in the G7 on Monday evening in New York City ahead of the United Nations General Assembly.
Canadian opposition New Democrat leader Jagmeet Singh, who is himself Sikh, called it outrageous and shocking. Singh said he grew up hearing stories that challenging India's record on human rights might prevent you from getting a visa to travel there.
"But to hear the prime minister of Canada corroborate a potential link between a murder of a Canadian citizen on Canadian soil by a foreign government is something I could never have imagined," Singh said.
The World Sikh Organization of Canada called Nijjar an outspoken supporter of Khalistan who "often led peaceful protests against the violation of human rights actively taking place in India and in support of Khalistan."
"Nijjar had publicly spoken of the threat to his life for months and said that he was targeted by Indian intelligence agencies," the statement said.
Nijjar's New York-based lawyer, Gurpatwant Singh Pannun, has said Nijjar was warned by Canadian intelligence officials about being targeted for assassination by "mercenaries" before he was gunned down.
India's main opposition party issued a statement backing Modi's position. The Congress Party wrote that "the country's interests and concerns must be kept paramount at all times" and that the fight against terrorism has to be uncompromising, especially when it threatens the nation's sovereignty.
Indian authorities have targeted Sikh separatism since the 1980s, when an armed insurgency for an independent Sikh state took off in Punjab state.
In 1984, Indian forces stormed the Golden Temple in the state's Amritsar city to flush out Sikh separatists, who had taken refuge there. The controversial operation killed around 400, according to official figures, although Sikh groups estimate the toll to be higher.
The prime minister who ordered the raid, Indira Gandhi, was killed afterwards by two of her bodyguards, who were Sikh. Her death triggered a series of anti-Sikh riots, in which Hindu mobs went from house to house across northern India, pulling Sikhs from their homes, hacking many to death and burning others alive.