Canadian Prime Minister Justin Trudeau Thursday reiterated that there are "credible allegations" that should be taken "extremely seriously" as he urged the government of India to work with his country to allow justice to follow its course in the killing of a Khalistani extremist leader.

"We call upon the government of India to take this matter seriously and to work with us to shed full transparency and ensure accountability and justice in this matter," he said while responding to questions on the diplomatic row between India and Canada.

"We are a country of the rule of law. We are going to continue to do the work necessary to keep Canadians safe and to uphold our values and the international rules based order. That's our focus right now," Trudeau said when asked whether his government will take any retaliatory measures following India's suspension of visa services for Canadians.

Tensions flared between India and Canada early this week following Trudeau's explosive allegations of a "potential" involvement of Indian agents in the killing of Khalistani extremist Hardeep Singh Nijjar on his country's soil on June 18 in British Columbia. India had designated Nijjar as a terrorist in 2020.

India angrily rejected the allegations as "absurd" and "motivated" and expelled a senior Canadian diplomat in a tit-for-tat move to Ottawa's expulsion of an Indian official over the case.

"Of course, there are credible allegations that we need to take extremely seriously as Canadians and indeed as a world," Trudeau asserted when asked if the evidence suggested by him was extensive in the matter.

Trudeau also said that his government was not looking to provoke or cause problems.

"There is no question that India is a country of growing importance and a country that we need to continue to work with, not just in the region but around the world. We're not looking to provoke or cause problems. But we are unequivocal around the importance of the rule of law and unequivocal about the importance of protecting Canadians.

"That's why we call upon the government of India, to work with us to establish processes to discover and to uncover the truth of the matter and to allow justice and accountability to be served," he added.

On Thursday, India asked Canada to come down hard on terrorists and anti-India elements operating from its soil and suspended visa services for Canadians, as escalating tensions between the two nations over the killing of Nijjar pushed their ties to an all-time low.

India also asked Canada to downsize its diplomatic staff in the country, arguing that there should be parity in strength and rank equivalence in the mutual diplomatic presence. The size of Canadian diplomatic staff in India is larger than what New Delhi has in Canada.