Hyderabad: RGI Airport policeregistered a case against an unknown passenger for leaving a message in an Air India flight’s toilet on Monday, claiming a bomb was placed aboard the aircraft. After a thorough inspection, CISF personnel declared that there were no explosive materials inside the aircraft and it was a hoax.At 11pm, an Air India’s Kolkata-Hyderabad flight landed at the RGI Airport.While passengers were disembarking, one of them alerted the flight crew about a note left by an unknown person in the plane’s toilet. “On the tissue paper, someone wrote: Inform Captain, unidentified object is in this aircraft. It will blast,” a RGI Airport official said.Alerted by the crew, CISF personnel conducted a thorough check of the aircraft and declared that there were no explosives aboard. “It was a hoax. We registered a case on the complaint of GMR authorities,” RGI Airport sub-inspector (SI) Appa Rao said.The case was registered under Sections 351 (4) (Criminal intimidation by an anonymous communication) and 353 (2) (Statements conducing to public mischief) of the BNS on Tuesday. Police were yet to identify the prankster.