US Ambassador to Canada David Cohen has confirmed that "shared intelligence among Five Eyes partners" had informed Canadian Prime Minister Justin Trudeau of the possible involvement of Indian agents in the murder of a Canadian citizen in June, CTV News reported.

Intelligence-sharing network Five Eyes includes the US, Britain, Canada, Australia and New Zealand.

Trudeau said on Monday that Ottawa had credible intelligence linking Indian agents to the murder of Sikh separatist leader Hardeep Singh Nijjar in Vancouver, prompting an angry reaction from New Delhi, which denies the allegation.

"I will say this was a matter of shared intelligence information. There was a lot of communication between Canada and the United States about this, and I think that's as far as I'm comfortable going," Cohen told CTV News in an interview to be aired on Sunday.

The Canadian government amassed intelligence from both human and electronic sources in a months-long investigation into the murder, CBC News reported separately on Thursday.

Cohen did not comment to CTV News on the type of intelligence that had informed the Canadian government.

Pressure from US

The US made clear on Friday that it expected the Indian government to work with Canada on efforts to investigate the possible involvement of New Delhi agents in Nijjar's murder.

"We are deeply concerned about the allegations that Prime Minister Trudeau has raised," US Secretary of State Antony Blinken told reporters in a press briefing.

"It would be important that India work with the Canadians on this investigation. We want to see accountability."

India, which rejected the allegation as "absurd," has stopped issuing visas to Canadian citizens due to "security threats."

Trudeau, however, said he was not looking to provoke India and urged Indian officials to cooperate with the investigation into the killing.

Nijjar, a plumber who was born in India and became a Canadian citizen in 2007, had been wanted by India for years before he was gunned down in June outside the temple he led in Surrey, a suburb of Vancouver.

The Khalistan movement for an independent Sikh state in India peaked in the 1980s.

It was quelled by force, and most of its leaders are now said to be based in Canada, Australia and the UK.