India on Wednesday advised its citizens to be careful when traveling to Canada as a rift between the two nations widens further in the wake of Ottawa’s allegations that India may have been involved in the killing of a Sikh separatist leader in suburban Vancouver.

The foreign ministry in New Delhi issued an updated travel advisory, urging its nationals and especially those studying in the North American country to be cautious because of “growing anti-India activities and politically condoned hate-crimes.”

Indians should also avoid going to venues in Canada where “threats have particularly targeted Indian diplomats and sections of the Indian community who oppose anti-India agenda,” the ministry said.

Ottawa and New Delhi, two key strategic partners on security and trade, are locked in a diplomatic tussle after Canada’s Prime Minister, Justin Trudeau, alleged that India was connected to the assassination of Sikh independence advocate on its soil in June.

Who was Hardeep Singh Nijjar, the Sikh activist whose killing has divided Canada and India?

Canada has yet to provide any evidence of Indian involvement in the assassination of Hardeep Singh Nijjar, a 45-year-old Sikh leader killed by masked gunmen in Surrey, outside Vancouver.

For years, India has said Nijjar, a Canadian citizen born in India, has links to terrorism, an allegation he denied. Nijjar was working to organize an unofficial Sikh diaspora referendum on independence from India at the time of his killing.

Trudeau’s announcement was followed by Canada expelling an Indian diplomat in Ottawa. New Delhi responded by rejecting Trudeau’s accusation as “absurd and motivated” and later expelling a Canadian diplomat.

India expels Canadian diplomat, escalating tensions after Trudeau accuses India in Sikh's killing

Indian authorities designated Nijjar a terrorist in 2020 and accused him of supporting demands for an independent Sikh homeland, known as Khalistan, that started as an insurgency in India’s Punjab state in 1970s and 1980s and was crushed in an Indian government crackdown.

The movement has since lost much of its political power but still has supporters in Punjab, where Sikhs are in a majority, as well as among the sizable overseas Sikh diaspora.

India’s foreign ministry also said Trudeau’s 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.”

The ministry regularly issues travel advisories. In September last year, it asked Indian citizens to remain cautious while traveling in Canada because of “sharp increase in incidents of hate crimes, sectarian violence and anti-India activities” there.

What to know about the Sikh movement at the center of the tensions between India and Canada

The modern Sikh independence movement reaches back to the 1940s but eventually morphed into the 1970s and 1980s insurgency. In 1984, then-Prime Minister Indira Gandhi ordered a raid to capture armed separatists taking refuge in Sikhism’s holiest shrine.

The raid killed hundreds of people, and two of Gandhi’s Sikh bodyguards assassinated her shortly after. In response, anti-Sikh riots took place across India in which members of the minority were dragged out of their homes and killed.

And though the insurgency was suppressed long ago, the government of Prime Minister Narendra Modi has warned repeatedly that Sikh separatists were trying to make a comeback. Modi’s government has been asking several countries — including Canada, Australia and the United Kingdom — to take legal action against Sikh separatists.

Canada expels Indian diplomat as it investigates Sikh activist's killing

India has also for years accused Canada of giving free rein to Sikh separatists, including Nijjar.

The dueling expulsions of diplomats have escalated tensions — Trudeau had frosty encounters with 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.

Canada remains a top study destination for Indian students. In 2022, the country had nearly 300,000 Indians students pursuing higher education there.