CNN  — 

Canada’s accusation that India may have been involved in the assassination of a Sikh activist on its soil has triggered a growing spat with Ottawa and New Delhi both expelling senior diplomats, sending relations between the two countries plunging.

The tit-for-tat diplomatic expulsions came after Prime Minister Justin Trudeau said Canada was investigating “credible allegations” linking India to the June killing of Canadian citizen and prominent Sikh leader, Hardeep Singh Nijjar.

“Over the past number of weeks, Canadian security agencies have been actively pursuing credible allegations of a potential link between agents of the government of India and the killing of a Canadian citizen Hardeep Singh Nijjar,” Trudeau said in parliament on Monday, adding his government would take all steps necessary “to hold perpetrators of this murder to account.