Ties between the two countries have become seriously strained over Canadian suspicion that Indian government agents were linked to the murder of a Sikh separatist leader and Canadian citizen.

The Financial Times says India has threatened to revoke the diplomatic immunity of those diplomats told to leave who remain after Oct 10.

Relations between India and Canada have been tense of late, mostly due to the presence of Sikh separatists in Canada who have kept alive the demand for an independent Sikh state.

India has dismissed Canada's allegations as absurd, and ties have become strained with both governments expelling a diplomat in a tit-for-tat move.

Trudeau also says Ottawa has already reached out to Kyiv and Ukrainian President Volodymyr Zelensky through diplomatic channels to apologise.

Allies of Canada, including the US, have cautiously expressed concern over the claims and urged India to cooperate with Canada's investigation.

The episode played into the narrative promoted by Russian President Vladimir Putin that he sent his army into Ukraine last year to 'demilitarise and denazify' the country.

Yaroslav Hunka received two standing ovations from Canadian lawmakers in the House of Commons lower chamber during a visit by Ukrainian President Volodymyr Zelensky.

Canada is home to about 770,000 Sikhs – the highest population of Sikhs outside their home state of Punjab.

A blanket suspension of new visas by India for a Western country is unheard of and marks the lowest point of India-Canada relations.

Prime Minister Justin Trudeau condemns the protesters, calling them homophobic and transphobic.

The Indian foreign ministry says Canada has not shared any specific information about the murder.