Security was tightened at the Delhi airport on Wednesday after it received threat calls regarding two Air India flights, scheduled to take off for London the next day, News18 reported.

“We have got inputs that Sikhs for Justice has threatened that two Air India flights scheduled for London tomorrow won’t be allowed to operate,” said Rajeev Ranjan, deputy commissioner of police, Indira Gandhi International Airport. The Sikhs for Justice is a United States-based fundamentalist organisation.

The airport was placed on high alert after a meeting of all stakeholders. The threat coincides with the 1984 anti-sikh riots that took place in the first week of November.

The Union Ministry of Home Affairs had in July 2019 banned the Sikhs for Justice under the Unlawful Activities Prevention Act for alleged anti-national activities. The group has been pushing for a referendum in 2020 on the creation of Khalistan, a Sikh homeland carved out of India. The campaign also seeks to “end Indian occupation of Punjab”.

In 2018, India had issued a demarche notice to the United Kingdom against a proposed meeting by the group to gather support for the referendum campaign.