Indian Prime Minister Narendra Modi has expressed "strong concerns" to Canada over its handling of the Punjabi independence movement, on the same day the Sikh community in Metro Vancouver held a vote on the matter.

A statement released by India's Ministry of External Affairs says Modi told Canadian Prime Minister Justin Trudeau on the sidelines of this weekend's G20 summit in New Delhi that progress in the two countries' relationship requires "mutual respect and trust."

It says Modi described the Sikh movement as "promoting secessionism and inciting violence" against Indian diplomats, calling on Canada to work with India on what New Delhi deems a threat to the Canadian Indian diaspora.

The meeting between Modi and Trudeau coincided with voting in British Columbia on a non-binding referendum for a Sikh homeland that supporters call Khalistan.

Large crowds of voters lined up to vote at Surrey's Guru Nanak Gurdwara on Sunday, after the Surrey School District cancelled organizers' original plans to rent a local high school for the vote, which is part of an international campaign.

Modi's comments come after India's High Commissioner in Ottawa, Sanjay Kumar Verma, recently said Canada is adequately protecting his country's diplomats, and closer ties are possible despite heated diaspora politics.