India expelled one of Canada’s top diplomats Tuesday, ramping up a confrontation between the two countries over Canadian accusations that India may have been involved in the killing of a Sikh separatist leader in suburban Vancouver. India, which has dismissed the accusations as absurd, said the expulsion came amid “growing concern at the interference of Canadian diplomats in our internal matters and their involvement in anti-India activities," according to a statement from its Ministry of External Affairs. Prime Minister Justin Trudeau appeared to try to calm the diplomatic clash Tuesday, telling reporters that Canada is “not looking to provoke or escalate." Canada expels Indian diplomat as it investigates Sikh activist's killing “We are simply laying out the facts as we understand them and we want to work with the government of India to lay everything clear and to ensure there are proper processes,” he said. "India and the government of India needs to take this matter with the utmost seriousness.” On Monday, Trudeau said there were “credible allegations” of Indian involvement in the slaying of Hardeep Singh Nijjar, a 45-year-old Sikh leader who was killed by masked gunmen in June in Surrey, outside Vancouver. For years, India has said Nijjar, a Canadian citizen born in India, has links to terrorism, an allegation Nijjar denied. What to know about the Sikh movement at the center of the tensions between India and Canada A U.S. official said Trudeau was in contact with President Joe Biden's administration about Canada’s findings before raising them publicly. The official, who was not authorized to comment publicly and spoke on condition of anonymity, said Trudeau’s willingness to speak out about the matter was taken by the White House as an indication of the Canadian leader's certainty about what had been found. Canada has yet to provide any evidence of Indian involvement, but if true it would mark a major shift for India, whose security and intelligence branches have long been significant players in South Asia, and are suspected in a number of killings in Pakistan. But arranging the killing of a Canadian citizen in Canada, home to nearly 2 million people of Indian descent, would be unprecedented. India, though, has accused Canada for years of giving free rein to Sikh separatists, including Nijjar. The dueling expulsions have escalated tensions between Canada and India. Trudeau had frosty encounters with Indian Prime Minister Narendra Modi during this month's Group of 20 meeting in New Delhi, and a few days later Canada canceled a trade mission to India planned for the fall. India dismisses allegations of killing Sikh activist in Canada as 'absurd', expels senior Canadian diplomat 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 decadelong 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. Violence spilled across years and continents. In 1984, former Indian Prime Minister Indira Gandhi was killed by two of her Sikh bodyguards after she ordered an army operation to flush out heavily armed Sikh separatists barricaded inside Sikhism’s holiest shrine. Her killing led to riots that left more than 2,000 Sikhs dead. The next year, an Air India jetliner flying from Toronto to New Delhi was destroyed by a bomb over the Irish coast, killing 329 people. Officials blamed Sikh separatists. 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 sizable 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. Nijjar was wanted by Indian authorities, who had offered a reward for information leading to his arrest. At the time of his killing he was working with the group Sikhs For Justice, organizing an unofficial Sikh diaspora referendum on independence from India. Gurpatwant Singh Pannun, a lawyer and spokesperson for Sikhs For Justice, has said Nijjar was warned by Canadian intelligence officials about being targeted for assassination by “mercenaries.” Nijjar had recently been meeting “once or twice a week” with Canadian Security Intelligence Service officers, including a day or two before the shooting, said his son Balraj Singh Nijjar. He said his father had received hundreds of threatening messages telling him to stop his advocacy for Sikh independence. The threats were always passed to authorities. “We weren’t worried about safety because we weren’t doing anything wrong," he said. “We were just using freedom of speech.” He said the family was relieved by Canada's actions. "From day 1 we kind of had this idea and knowledge that if anything would happen to him, the Indian government would be involved,” he said. “It was just a matter of time for when the truth would come out. It’s finally coming to the public eyes that the Indian government is involved in this.” On Monday, Trudeau told Parliament that Canadian security agencies were investigating “credible allegations of a potential link between agents of the government of India" and Nijjar's killing. “Any involvement of a foreign government in the killing of a Canadian citizen on Canadian soil is an unacceptable violation of our sovereignty,” he said. India’s foreign ministry dismissed the allegation as “absurd” and accused Canada of harboring “terrorists and extremists.” “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 said in a statement Tuesday. India has long demanded that Canada take action against the Sikh independence movement, which is banned in India. Canada has a Sikh population of more than 770,000, about 2% of its population. In March, Modi's government summoned the Canadian high commissioner in New Delhi, the top diplomat in the country, to complain about Sikh independence protests in Canada. In 2020, India’s foreign ministry also summoned the top diplomat over Trudeau's comments about an agricultural protest movement associated with the state of Punjab, where many Sikhs live. Critics accuse Modi’s Hindu nationalist government of seeking to suppress dissent using sedition laws and other legal weapons. Some critics of his administration have been arrested, creating what Modi’s opponents say is a culture of intimidation. Trudeau said Monday he brought up Nijjar’s slaying with Modi last week at the G20 meeting in New Delhi, and told him any Indian government involvement would be unacceptable and he asked for cooperation in the investigation. Modi, for his part, expressed “strong concerns” over Canada’s handling of the Sikh independence movement at that meeting, India’s statement said. While in New Delhi, Trudeau skipped a dinner hosted by the Indian president, and local media reports said he was snubbed by Modi when he got a quick “pull aside” instead of a bilateral meeting. The statement called on Canada to work with India on what New Delhi said is a threat to the Indian diaspora, and accused the Sikh movement of “promoting secessionism and inciting violence” against Indian diplomats. Earlier this year, Sikh protesters pulled down the Indian flag at India’s high commission in London and smashed the building’s window after India arrested a popular Sikh preacher. Protesters also smashed windows at the Indian Consulate in San Francisco and skirmished with consulate workers. The British government, meanwhile, said Tuesday there were no plans to reinvestigate the death of a U.K-based Sikh activist in the wake of Canada’s claim India might have been behind the slaying of Nijjar. Avtar Singh Khanda, who played a prominent role in protests for an independent Sikh homeland, died in June in the English city of Birmingham after falling ill. Supporters alleged be might have been poisoned, but Prime Minister Rishi Sunak’s spokesman, Max Blain, said police found nothing suspicious. The Trudeau government’s allegations are awkward for the U.K., which is a close ally of Canada in the “Five Eyes” intelligence-sharing alliance that also includes the U.S., Australia and New Zealand, and is also seeking a free trade deal with India. “These are serious allegations. It is right that the Canadian authorities should be looking into them,” Blain said, adding it would be inappropriate to comment further while the investigation is underway.