Washington, Sep 24 : After Khalistani terrorist Hardeep Singh Nijjar was shot dead outside a Gurdwara in British Columbia, the Federal Bureau of Investigation (FBI) agents visited several Sikh leaders and warned them that their lives were also at risk, as per a report in The Intercept. Pritpal Singh, a political activist who is a coordinator for the American Sikh Caucus Committee, told The Intercept that he and two other Sikh Americans in California received calls and visits from the FBI after Nijjar was killed. Sukhman Dhami, co-director of Ensaaf, a California-based nonprofit group said Sikhs throughout the US have received police warnings about potential threats. India and Canada are enmeshed in a diplomatic row over Canadian Prime Minister Justin Trudeau's allegation of involvement of Indian intelligence and the state in the killing of Canadian citizen and Sikh separatist Nijjar. Nijjar was declared designated terrorist by India in 2020. India had rejected claims by the Canada government terming them as "absurd and motivated". Both countries announced tit-for-tat expulsions of senior diplomats and issued travel advisories. "Based on a month-long investigation into Nijjar's death, the Canadian government had amassed both human and signals intelligence which includes communications involving Indian officials including Indian diplomats present in Canada," public broadcaster Canadian Broadcasting Corporation (CBC) reported quoting government sources. Some of the intelligence was provided by an unnamed ally in the Five Eyes intelligence alliance, that consists of the US, the UK, Australia, Canada and New Zealand, the CBC reported on Thursday. /IANS