A "security threat" was issued online, prompting an Air India plane to make an emergency landing in Canada. According to the airline, the flight heading for Chicago stopped at Iqaluit, where passengers were taken off and "re-screened".A statement put online stated that it had received "a number of threats in recent days," all of which turned out to be hoaxes.The emergency landing comes less than a day after Canada and India’s row over the murder of a Sikh seperatist deepened.On Monday, Canada expelled six Indian diplomats, including the high commissioner, on charges related to the death of Hardeep Singh Nijjar. India replied by expelling six high-ranking Canadian diplomats, including the acting high commissioner, and announcing the withdrawal of its envoy from Canada.The diplomatic row marks a significant deterioration in relations between the two Commonwealth countries. Ties have deteriorated since Canadian Prime Minister Justin Trudeau revealed last year that he had proof linking Indian operatives to the death of the Sikh leader on Canadian soil.