India’s prime minister, Narendra Modi, has condemned a “deliberate attack” on a Hindu temple in Canada, blaming Sikh activists for the violent clash at a time of escalating diplomatic tensions between the two countries. Videos on social media showed demonstrators protesting outside the Hindu Sabha Mandir temple in the city of Brampton, where Indian diplomats were visiting ahead of Diwali celebrations. Some protesters held yellow Khalistan flags, representing a region of India they hope to one day carve out as a Sikh homeland. As tensions rose, isolated fights broke out. Canada’s Peel regional police said on Monday that three people had been “arrested and criminally charged” following the attack and they were investigating “several acts of unlawfulness”. The alleged offences include assault with a weapon and assaulting a police officer. In the hours after the clashes, each side blamed the other for inciting violence. Modi denounced “cowardly attempts to intimidate” consular staff, writing in a post on social media: “Such acts of violence will never weaken India’s resolve.” The group Sikhs for Justice alleged in a statement the protest “turned violent” when a group of “Indo-Canadian nationalists, incited by Indian consulate officials” attacked the Sikh demonstrators. The group says some attenders retreated into the temple and began throwing rocks and wielding iron rods. Canadian federal party leaders all condemned the violence. “Every Canadian has the right to practice their faith freely and safely,” Justin Trudeau wrote on social media. The Conservative leader, Pierre Poilievre, “unequivocally” condemned violence “targeting worshippers” and Jagmeet Singh, leader of the New Democratic party also “unequivocally” condemned the clashes. “Violence anywhere is wrong,” he wrote. The Ontario premier, Doug Ford, said the violence was “completely unacceptable and must be condemned”. Relations between India and Canada have remained tense ever since Trudeau publicly accused the Indian government of assassinating Hardeep Singh Nijjar, a prominent Khalistan activist. Tensions rose in October when Canada expelled six Indian diplomats including the country’s high commissioner. The move came as federal police warned of a vast, covert network of violence operated by the Indian government in Canada. Indian officials, conversely, say Canada has ignored the rise of Sikh separatism and done little to tamp down on what Delhi says is violent rhetoric.