The latest flare-up in diplomatic tensions comes a year after Ottawa accused New Delhi of being involved in the assassination of a Sikh separatist leader on Canadian soil.

A diplomatic situation involving "serious criminal activity" by India's diplomats has forced the Royal Canadian Mounted Police to break protocol and speak publicly about ongoing threats to Canada, officials said Monday.

Relations between India and Canada are at a low point as the countries expelled each other’s top diplomats over an ongoing dispute about the killing of a Sikh activist in Canada

The diplomatic rift has suddenly grown more stark as Canada amplifies its accusations that India is directing lethal operations abroad.

Prime Minister Justin Trudeau accused Indian diplomats of backing a pattern of criminal harassment and violence against Canadians, escalating a dispute that began last year when he suggested Indian agents were involved in the murder of a Canadian Sikh activist in British Columbia.

Canada's Prime Minister Justin Trudeau accused India Monday of making a "fundamental error," as an escalating row over the killing of a Sikh separatist on Canadian soil last year saw both countries expel each other's ambassadors.