The threat - the first ever in Manipur - was caused by a passenger on the Air Asia flight.
An Air Asia flight from Imphal was held up on Thursday and extensively searched after a passenger told the cabin crew he was carrying a bomb. Though it was later declared a hoax, the passenger has been arrested and is being questioned.
The threat - the first ever in Manipur - triggered panic and alarm in Tulihal international airport in Imphal. Apart from the thorough search of the plane, including unloading the luggage for a detailed check, passengers on other flights were not allowed to disembark and security was tightened across the airport.
CISF personnel conducted the search inside the Air Asia flight which was to leave the airport at 11.30 am for Guwahati in Assam.
Officials said the passenger, identified as Paocha Robinson, who boarded the flight at 11.20 am unnerved the cabin crew as he told them he was carrying a bomb.
Mr Robinson, after being arrested, was subjected to detailed interrogation to establish his motive and antecedents. "It is not ruled out that he is innocent. There must be good reasons for the bomb hoax. We are exploring all angles," said sources.
Security was beefed up in and around the international airport. Only passengers with valid tickets are allowed in the interior enclosures.
The flight was eventually allowed to leave for Guwahati at 2.04 pm.