India has stopped issuing visas to Canadian citizens amid a row over the killing of a Canadian religious leader. Ottawa has alleged that New Delhi was involved.

India announced the move on Thursday. It categorically denies any links to the murder, saying Canada has shown no evidence of Indian involvement.

Canadian Prime Minister Justin Trudeau alleged on Monday that the Indian government had been involved in the fatal shooting of a Sikh leader in Canada in June. The victim was reportedly a supporter of the Sikh independence movement in northern India.

Trudeau told reporters in New York on Thursday that his country is "not looking to provoke or cause problems" with India, but is defending the rule of law.

Trudeau called the issue "something of the utmost and foundational importance" for Canada. He urged India to work with Canada to investigate the killing.

The US government appears cautious about the dispute as Washington is seeking to strengthen ties with New Delhi.

US National Security Advisor Jake Sullivan said at a news conference on Thursday that the White House has "deep concerns about the allegations."

Asked if the issue could drive a wedge between the US and India, Sullivan said Washington has been and will continue to be in touch with New Delhi over the matter.