Trudeau's first bilateral visit to India was hit by a controversy over the dinner invitation to Atwal by the Canadian High Commissioner in New Delhi.
Atwal had been convicted of shooting at visiting Punjab cabinet minister Malkiat Singh Sidhu on Vancouver Island in 1986.
High Commissioner Nadir Patel cancelled Atwal's invite for the dinner, hosted last night for Trudeau, while the ministry of external affairs (MEA) said it will "ascertain" how Atwal entered India.
The informant, who asked not to be identified for fear of retaliation, confirmed speaking to an agent from the Canadian Security Intelligence Service (CSIS) on February 17, hoping to alert the Canadian government to Atwal's criminal history.
The person said to the CSIS agent that "this is an embarrassment for the prime minister and CSIS should send a note to the prime minister's office. And they sent a note".
CSIS did not respond to requests for comment, Postmedia reported.
A separate source told Postmedia that some members of the Punjabi-language media in Surrey sent news reports about Atwal's history to the Canadian High Commission in New Delhi on February 20.
The source said it was widely known that Atwal, a former member of the terrorist International Sikh Youth Federation, was going to India to attend some of the events with Prime Minister Trudeau and the Canadian delegation.
The outcome has embarrassed Trudeau, who had made efforts in India to insist Canada is not soft on Sikh separatism and believes in a united India, the Vancouver Sun said.
Atwal was also once accused of assaulting Indian-origin former British Columbia premier Ujjal Dosanjh.
Dosanjh said the Canadian government demonstrated a lack of concern by inviting the man convicted of attempted murder in another case.
Dosanjh, also a one-time federal Liberal cabinet minister, says he was taken aback when he found out that Atwal was invited to a dinner reception with the prime minister after attending another event with the Trudeau family earlier this week, the Globe and Mail reported.
He said Atwal attacked him with an iron bar in 1985 over his opposition to Sikh extremism. The assault left Dosanjh with 80 stitches and a broken hand, but Atwal was acquitted of the crime.
"It left me speechless about the lack of preparation or the depth of unpreparedness with which Mr Trudeau's trip went through," he said.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
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