The Canadian government expelled six Indian diplomats on Monday after accusing New Delhi of waging a vast campaign of violence, espionage and intimidation against dissidents on Canadian soil. India expelled six Canadian diplomats in response.

The allegations have pushed relations between the two democracies to an unprecedented level and build on Canadian Prime Minister Justin Trudeau’s shocking accusations last year that India was involved in the murder of Canadian citizen Hardeep Singh Nijjar and Sikh separatist leader described as a “terrorist” by New Delhi.

At a news conference Monday, Canada’s Thanksgiving holiday, Trudeau said investigators had “clear and convincing evidence that agents of the Indian government have engaged and continue to engage in activities that pose a threat important for public safety.

These activities, he said, include “clandestine information gathering techniques, coercive behavior targeting Canadians of South Asian origin, and participation in more than a dozen threatening and violent acts, including including murders.”

“This is unacceptable,” he added.

Indian agents in Canada have also used organized crime to target Canada’s South Asian community, Royal Canadian Mounted Police Assistant Commissioner Brigitte Gauvin said at an earlier news conference. An Indian organization called “the Bishnoi Group,” she explained, was linked to the Indian government.

Lawrence Bishnoi, accused by India’s National Investigation Agency of organizing a criminal syndicate, is currently awaiting trial in the west of the country on terrorism charges.

The alleged interference was not limited to Canada. Last year, U.S. officials said they had foiled a plot by an Indian agent to assassinate a Sikh leader in New York.

India said it withdrew its diplomats from the country after Canada declared them “persons of interest” as part of an internal investigation. “The Indian government strongly rejects these absurd imputations and attributes them to the political agenda of the Trudeau government,” the Indian foreign ministry said in a statement on Monday.

Murder of Sikh leader on Canadian soil sparks diplomatic row

The deterioration of diplomatic relations between the two countries was triggered by Nijjar’s fatal shooting outside a Sikh temple in Surrey, a Vancouver suburb with a large Sikh population, in June last year.

Nijjar, 45, was a leader in the movement to create part of Indian Territory as a homeland for the Sikh population. He was named head of the Khalistan Tiger Force, a militant organization within the movement that India labels a terrorist group. In Surrey he ran a Sikh place of worship.

More: Canada says India helped assassinate Sikh activist: Who was Hardeep Singh Nijjar? The gap between countries is widening

The Indian government began searching for Nijjar in 2007, in connection with the bombing of a movie theater in the state of Punjab. At that time, Nijjar had already been living in Canada for a decade. He obtained his Canadian citizenship in 2015.

Canada’s suspicions that India was involved in Nijjar’s death prompted the country to suspend trade treaty negotiations and expel their respective diplomats last September.

Contributor: Reuters

This article originally appeared on USA TODAY: Diplomatic fallout between Canada and India deepens