NEW DELHI, India (AFP) — India criticised Canada on Monday saying Ottawa was investigating its ambassador and other diplomats as “persons of interest”, after the killing last year of a Sikh separatist leader.

The 2023 murder of Canadian citizen Hardeep Singh Nijjar crashed diplomatic relations with India after Prime Minister Justin Trudeau said there were “credible allegations” linking Indian intelligence to the crime.

India’s foreign ministry said in a statement it had “received a diplomatic communication from Canada suggesting that the Indian High Commissioner and other diplomats are persons of interest” in the ongoing investigation.

Nijjar — who immigrated to Canada in 1997 and became a citizen in 2015 — had advocated for a separate Sikh state, known as Khalistan, carved out of India.

He had been wanted by Indian authorities for alleged terrorism and conspiracy to commit murder.

Four Indian nationals have been arrested in connection with Nijjar’s murder, which took place in the parking lot of a Sikh temple in Vancouver in June 2023.

India on Monday called allegations it was connected to the killing as “preposterous” and a “strategy of smearing India for political gains”.

Last year it briefly curbed visas for Canadians and forced Ottawa to withdraw diplomats, and on Monday threatened further action.

“India now reserves the right to take further steps in response to these latest efforts of the Canadian Government to concoct allegations against Indian diplomats,” the foreign ministry said.

Canada is home to some 770,000 Sikhs, who make up about two percent of the country’s population, with a vocal minority calling for an independent state of Khalistan.

In November 2023, the US Justice Department also charged an Indian citizen living in the Czech Republic with allegedly plotting a similar assassination attempt on US soil.

Prosecutors said in unsealed court documents that an Indian government official was also involved in the planning.