India on Wednesday urged its nationals in Canada, especially students, to exercise "utmost caution" as ties deteriorate after each nation expelled one of the other's diplomats in an escalating row over the murder of a Sikh separatist leader.

Tension has grown since Prime Minister Justin Trudeau said on Monday Canada was investigating "credible allegations" about the potential involvement of Indian government agents in the murder of Hardeep Singh Nijjar in British Columbia in June.

"In view of growing anti-India activities and politically condoned hate crimes and criminal violence in Canada, all Indian nationals there, and those contemplating travel, are urged to exercise utmost caution," India's foreign ministry said, without providing evidence or details of specific incidents.

Just hours after India's travel advisory, Canada's public safety minister Dominic LeBlanc told reporters that Canada is a safe country.

Prime Minister Narendra Modi's government has categorically rejected Canada's suspicions that Indian agents had links to the murder.

"Given the deteriorating security environment in Canada, Indian students in particular are advised to exercise extreme caution and remain vigilant," the ministry added in a statement.

Canada has for months maintained a security advisory for India, urging citizens to "exercise a high degree of caution" in their travel to the South Asian country.

However, Canada issued a health advisory update for India on Monday related to COVID-19, measles and the Zika virus. The Canadian government said that update was part of a "pre-scheduled and routine maintenance in the section on travel health information."

Since 2018, India has been the largest source nation for international students in Canada.

That figure rose 47 percent last year to nearly 320,000, making up about 40 percent of total overseas students, according to the Canadian Bureau of International Education.

On Wednesday, a private entertainment company, BookMyShow, announced the cancellation of an India tour by Canadian singer Shubhneet Singh.

Canadian officials have so far declined to say why they believe India could be linked to Nijjar's murder.

Canada's allies

The United States has voiced "deep concern" over Canada's accusations and U.S. Ambassador to India Eric Garcetti said on Wednesday "those who are responsible must be held accountable."

The Washington Post reported Trudeau had pushed for a joint statement condemning India at last week's Group of 20 summit in New Delhi and was turned down by the United States and others.

White House national security adviser John Kirby said "any reports that we rebuffed Canada in any way whatsoever are false, and we will continue to coordinate and consult with them on this."

Britain, another key ally in the Five Eyes intelligence sharing alliance, refused to publicly criticize India and said bilateral trade talks will continue as planned. Indeed, a statement from Foreign Secretary James Cleverly about the affair did not mention India by name.

(Cover: Indian Prime Minister Narendra Modi (R) welcomes Canadian Prime Minister Justin Trudeau upon his arrival at Bharat Mandapam convention center for the G20 Summit in New Delhi, India, September 9, 2023. /CFP)

(With input from Reuters)