Mumbai Police registered a case against an unknown person after an IndiGo flight from Chennai to Mumbai received a bomb threat on Tuesday.

According to the Mumbai Police, about 40 kilometres away from Mumbai airport, a threatening letter was found in the airplane bathroom. Written on some tissue paper were the words, "There is a bomb in my bag, if we land in Bombay, everyone will die, I am a terrorist agency."

"After receiving this threatening letter, the local police and other agencies were informed about it," said the police. "As soon as the plane landed at the airport, all the passengers were hurriedly debarred and the plane was checked, but it was a matter of relief that nothing like this was found."

Mumbai Airport Police registered a case against an unknown person and initiated an investigation into the matter.