Ties between the two G20 nations plummeted to the lowest ever in September after Justin Trudeau accused New Delhi of being involved in the killing of a Canadian national linked to the secessionist Khalistan movement.
Gurpatwant Singh Pannun, a Canada-based separatist leader, released a video earlier this month where he repeated multiple threats of danger to those travelling by the Indian state carrier on 19 November.
“We are asking the Sikh people to not fly via Air India on 19 November. There will be a global blockade. Do not travel by Air India or your life will be in danger,” he said.
“It is my warning to the government of India,” added Mr Singh Pannun, who is also a designated terrorist in India.
Canadian transport minister Pablo Rodriguez in a social media post said the Trudeau administration "takes any threat to aviation extremely seriously".
"We are investigating recent threats circulating online closely and with our security partners. We will do everything necessary to keep Canadians safe," he added.
The Royal Canadian Mounted Police (RCMP) was reportedly working with its domestic and international partners as part of an investigation into the “threats” against the Air India flights.
The Canadian government had previously denounced an online hate video that was widely circulated during the initial days of the spat between the two countries.
Following the threats, authorities in India beefed up security at the capital New Delhi and neighbouring Punjab airports. All Air India passengers at Delhi and Punjab airports will be put through a “secondary ladder point check”, according to an order issued by the Bureau of Civil Aviation Security. The process involves an extra round of frisking of passengers and checking their bags at the aerobridge as they enter the aircraft.
Additionally, a pre-existing security alert issued for the festive season in October for all civil aviation installations has been extended till 30 November.
New Delhi said it would take up the threat against Air India flights originating from and terminating in Canada with concerned Canadian authorities.
However, Mr Singh Pannun told The Guardian that the video "clearly states I’m asking the global Sikh community to boycott Air India and instead Sikhs should fly Air Canada and British Airways".
"Where is the threat? There is none."
In 1985 an Air India flight was bombed in a terrorist attack orchestrated by Khalistan leaders. The Air India flight 182 from Montreal exploded off the coast of Ireland, killing 329 people on board.
"RCMP have every right to investigate a terror threat. And if they consider calls for boycott an act of civil disobedience, if that is terror, then so be it, let them investigate,” Mr Singh Pannun said.
“We are simply asking Sikhs not to make the decision to direct their money towards countries like India.”
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