A threat to take down the Indian flag and replace it with a banner for Khalistan in Delhi's Pragati Maidan, the venue for a high-profile G20 meeting in September, is being probed by the police, officials said on Saturday.
The police said they have launched an investigation after receiving a tip-off from someone who had received an audio recording from an unknown number two days ago.
The audio clip spoke about the massive crackdown in Punjab to search for radical Sikh preacher Amritpal Singh.
The audio message said supporters of Amritpal Singh would "take over" Pragati Maidan and pull down the flag of India. It also abused Prime Minister Narendra Modi and Home Minister Amit Shah.
The police filed a First Information Report or FIR, including charges of trying to stoke a riot and affect law and order. The audio recording was received by a passenger flying into the Delhi Airport.
The police have said they are trying to trace the origin of the audio clip amid efforts to catch Amritpal Singh, who has been on the run since last week.
They also said they had strengthened security at Pragati Maidan and other sensitive locations in the city.
Pragati Maidan is a large exhibition and convention centre in New Delhi, where many national and international events are held. The G20 meeting, which will bring together leaders of 20 major economies, is expected to be one of the biggest diplomatic events hosted by India this year.
The Delhi Police statement comes a day after they said they have opened an investigation into a protest this week at its High Commission in London, where protesters with Khalistan banners took an Indian flag down from a first-floor balcony of the building on Sunday to denounce the crackdown against Amritpal Singh.