Zee Media Bureau, New Delhi :In a security scare, the Air India crew on Friday night found a defused grenade in the business class of an Air India jumbo aircraft, which was kept as an emergency standby for Prime Minister Narendra Modi’s recent US visit.The grenade was found on board the Boeing 747-400 which was operating the Mumbai-Hyderabad-Jeddah flight, airline sources said on Saturday.Indian security agencies have launched an investigation into the discovery of the defused explosive.Confirming the development, Air India officials guardedly said that “a probe is under way” to unravel how, where and when the major security breach occurred.On landing at Jeddah, the incident was reported to the local security agencies who took over the aircraft, the sources said.According to AI sources, the Boeing 747 was an emergency standby aircraft intended for use by Prime Minister Narendra Modi in case his regular aircraft developed any last minute snags.The aircraft was kept in complete readiness at Indira Gandhi International Airport, New Delhi, and released on Friday for commercial operations after Modi’s return to India from the US on Thursday night.After release from standby VVIP duty, it was operated as a scheduled domestic-cum-international sector Delhi-Mumbai-Hyderabad-Jeddah flight.The aircraft, which has been cleared and released by Jeddah airport security, is still in the city as Indian security personnel were investigating the matter. The plane is likely to return to Calicut soon.The Prime Minister had undertaken a five-day visit to the US from September 25.