Canada announced the expulsion of six Indian diplomats Monday, including the high commissioner, after the police accused agents of the Indian government of being linked to homicides, harassment and other “acts of violence” against Sikh separatists in the country.

Canada’s Minister of Foreign Affairs Mélanie Joly said in a Monday statement that the decision to expel the diplomats “was made with great consideration and only after (Canadian police) gathered ample, clear and concrete evidence which identified six individuals as persons of interest in the Nijjar case.”

The extraordinary step has sharply escalated diplomatic tensions between the countries, with India swiftly expelling six Canadian diplomats in response, including the acting High Commissioner Stewart Ross Wheeler, according to a statement from India’s Ministry of External Affairs.

Relations between both countries hit rock bottom last year when Canadian Prime Minister Justin Trudeau said he had credible information linking the Indian government to the assassination on Canadian soil of prominent Sikh separatist Hardeep Singh Nijjar.

During a Monday press conference, Trudeau accused the Indian government of making “a fundamental error in thinking that they could engage in supporting criminal activity against Canadians here on Canadian soil, whether it be murders or extortion or other violent acts, is absolutely unacceptable for any country, any democracy, that upholds the rule of law.”

He said that was why the Royal Canada Mounted Police (RCMP) “chose to come out today and disrupt the pattern of Indian diplomats collecting, through questionable and illegal means, information on Canadian citizens that were then fed to criminal organizations that would then take violent actions from extortion to murder against Canadians.”

The Indian government has called the accusations “preposterous” and said it was withdrawing the officials expelled by the Canadian government. “There is a deliberate strategy of smearing India for political gains,” the statement added Monday. “The aspersions cast on (High Commissioner Sanjay Kumar Verma) are ludicrous and deserve to be treated with contempt.”

‘Serious threat to our public safety’

Earlier on Monday, the RCMP took the unusual step of publicly disclosing details of multiple investigations into the involvement of Indian government agents alleged to have taken part in “serious criminal activity” in Canada.

The decision to publicly disclose the investigations was taken “due to the significant threat to public safety” and after attempts to address the issue together with the Indian government had not yielded satisfactory results, RCMP Commissioner Mike Duheme told reporters.

Duheme said that since September last year, there had been “well over a dozen credible and imminent threats” to the lives of members of the South Asian community, and specifically the “pro-Khalistan movement,” referring to a separatist movement among supporters of Sikh independence.