Indian Prime Minister Narendra Modi has criticised the "cowardly attempts to intimidate our diplomats" in a deepening diplomatic row with Canada.

Both countries expelled each other's top envoys last month after Canadian officials accused India of being involved in violent acts targeting Indian dissidents on Canadian soil, something the country denies.

Modi's comments came after violence broke out at a Hindu temple in the Canadian city of Brampton on Sunday, which he has called a "deliberate attack".

"Such acts of violence will never weaken India’s resolve. We expect the Canadian government to ensure justice and uphold the rule of law," he wrote on X.

Local police said three people have so far been arrested and charged over the incident in Brampton, near Toronto, but did not provide further details.

The force said "several acts of unlawfulness continue to be actively investigated" by its officers.

An unverified video posted online appeared to show people carrying yellow flags of the Khalistan movement - which demands a separate Sikh homeland in India - clashing with others holding Indian flags.

India's foreign ministry said "extremists and separatists" were behind the violence, calling on the Canadian government to "ensure that all places of worship are protected from such attacks".

The North America-based activist group Sikhs for Justice, meanwhile, described the incident as an "unprovoked violent attack on peaceful pro-Khalistan demonstrators".

Justin Trudeau wrote on X that Sunday's violence was "unacceptable", adding that "every Canadian has the right to practice their faith freely and safely".

Relations between India and Canada have soured since Ottawa accused the Indian government of being behind the 2023 killing of Hardeep Singh Nijjar, a naturalised Canadian citizen who is labelled a terrorist in India.

India has vehemently denied this and other allegations and maintained that Canada has provided no evidence to support its claims.

Mr Nijjar had been a vocal supporter of the Khalistan movement and publicly campaigned for it.

The rift between Canada and India has raised questions over the impact it could have on the deep trade and immigration ties between both countries.

Bilateral trade is worth billions of dollars, and Canada is home to nearly 1.7 million people of Indian origin.

Neither country has yet imposed tariffs or other economic forms of retaliation, but experts caution that this could change and that a cooling relationship between India and Canada could hinder further economic growth.