India on Wednesday told its citizens to avoid travelling to parts of Canada, following a diplomatic row sparked by the allegation that New Delhi was involved in the killing of a Sikh separatist near Vancouver.

“Threats have particularly targeted Indian diplomats and sections of the Indian community who oppose the anti-India agenda,” a foreign ministry statement said, advising citizens to “avoid travelling to regions and potential venues in Canada that have seen such incidents”.

The diplomatic row began between the two countries when Canada’s Prime Minister Justin Trudeau said in an emergency statement to the House of Commons that any involvement of a foreign government in the killing of a Canadian citizen was “an unacceptable violation of our sovereignty”.

Read: How India’s spat with Canada could affect relations with US, UK and Australia

Later, Foreign Minister Melanie Joly said Canada expelled India’s top intelligence agent in the country. The Indian High Commission in Ottawa did not respond to requests for comment.

Canada said it was “actively pursuing credible allegations” linking Indian government agents to the murder of a Sikh separatist leader in British Columbia in June.

In a tit-for-tat move, a senior Canadian diplomat was ordered to leave India.

India’s Ministry of External Affairs also summoned Canadian High Commissioner to India Cameron MacKay, and was informed about the decision to expel a senior Canadian diplomat based in India.

A day earlier, Canada requested its citizens to exercise a “high degree of caution” while travelling to India.

“Exercise a high degree of caution in India due to the threat of terrorist attacks throughout the country,” the official advisory read.