A Canadian spy agency has warned that India is using cyber technology to track separatists abroad, a day after the country’s government accused a top Indian official of authorizing violence that included the killing of a Sikh activist in Vancouver.

In a report, Canada’s Communications Security Establishment (CSE) said India was using cyber capabilities “to track and surveil activists and dissidents living abroad” as well as stepping up cyber-attacks against Canadian government networks.

Canada is home to the largest Sikh community outside of India, and includes activists for an independent Sikh state.

Ottawa has accused India of orchestrating the 2023 killing in Vancouver of the 45-year-old naturalized Canadian citizen Hardeep Singh Nijjar, a prominent campaigner for “Khalistan”, the fringe separatist movement for an independent Sikh homeland in India’s Punjab state.

“It is clear that we are seeing India being an emerging [cyber] threat actor,” the CSE chief, Caroline Xavier, told a news conference.

In the report, her agency blamed the rift in bilateral relations between Canada and India for “very likely” driving this activity.

The report notes that after Canada’s accusations, “a pro-India hacktivist group” launched crippling DDoS attacks – flooding a system with online traffic to make it inaccessible to legitimate users – against Canadian websites including the military’s public site.

On Tuesday, officials revealed that Ottawa had traced a campaign targeting Canadian Khalistan activists to the highest levels of Prime Minister Narendra Modi’s government.

Testifying at a house of commons public safety and national security committee, the deputy minister of foreign affairs, David Morrison, confirmed a Washington Post story that implicated the Indian home affairs minister, Amit Shah, in the plot to intimidate and even kill Canadian Sikhs.

The Post cited an unnamed senior Canadian official as having said that Shah authorized an intelligence gathering and attacks campaign, including the 2023 killing of Nijjar.

Morrison said he was a source for the information, telling the committee: “The journalist called me and asked me if it was that person. I confirmed it was that person.”

The Canadian prime minister, Justin Trudeau, and the national police have said there are “clear indications” of India’s involvement in the murder, as well as a broad campaign of intimidation, violence and other threats against Khalistan activists.

India has dismissed the allegations.

Delhi and Ottawa earlier this month each expelled the other’s ambassador and other senior diplomats.

Four Indian nationals have been arrested in connection with the murder.