The diplomatic row between Canada and India escalates as New Delhi reportedly told Ottawa to repatriate 40 of its diplomats by 10 October.

Canadian foreign minister Melanie Joly was mum about the Financial Times report, only telling reporters in Montreal Tuesday that a dialogue with New Delhi was taking place "privately."

"We are in good ongoing conversations with the Indian government," she said.

"In moments of tensions, because indeed there are tensions between both our governments, more than ever it's important that diplomats be on the ground," Joly added.

Canadian Prime Minister Justin Trudeau described the situation as "extremely difficult."

A dialogue with New Delhi was taking place 'privately.'

"We're not looking to escalate. As I've said, we are going to be doing the work that matters in continuing to have constructive relations with India," he said Tuesday.

The Indian Ministry of Foreign Affairs also declined to comment on the report.

The diplomatic row was triggered by Trudeau's accusation last month that India was involved in the killing of Sikh leader and Canadian citizen Hardeep Singh Nijjar near Vancouver in June.

Ottawa subsequently expelled one Indian diplomat and New Delhi retaliated with the expulsion of a Canadian diplomat.

The Indian government also advised its nationals against traveling to parts of Canada and has temporarily stopped processing visa applications to that country.