Thiruvananthapuram/Bangalore/New Delhi, March 21 (IANS) Twenty-seven passengers had a close shave Sunday when an explosive, a cocktail of sulphur, potassium chlorate and aluminum powder, was found in the cargo section of a Kingfisher flight after it landed in Thiruvananthapuram from Bangalore.

A Central Industrial Security Force (CISF) official reportedly discovered the crude explosive, the size of a cricket ball and wrapped in a Malayalam newspaper, shortly after the plane landed at 8.25 a.m.

The discovery triggered panic alarms in Bangalore and Thiruvananthapuram, leading to a high-level investigation on how it got past the many layers of security. All passengers and crew, however, had deboarded safely.

'It is not a bomb but certainly one which is explosive in nature. We have decided to register an FIR (first information report),' Thiruvananthapuram police chief M.R. Ajith Kumar said.

The aircraft was quickly cordoned off and searched before it was allowed to return to Bangalore later in the afternoon.

Officials at Bangalore were also perplexed as to how the explosives got into the aircraft.

'We have seen the CCTV footage at the cargo section and clippings from baggage screening and questioned people on duty at various checkpoints Sunday morning. We have not yet got any clue to how and at which place the device found its way to cargo hold of the flight,' a Bangalore police spokesperson told IANS late Sunday.

'A team from Bangalore is likely to be sent to Thiruvanathapuram late Sunday or early Monday to join the Kerala police in the probe,' he said.

Kerala Inspector General of Police A. Hemachandran said: 'The explosives were small in quantity. Yes, if the quantity was large, then things would have been different. We have already identified the passengers, crew and workers (who attended to the plane) and begun the probe.'

Ajith Kumar said: 'We are investigating how this happened. Certainly this is a security lapse.'

A civil aviation ministry official told IANS in New Delhi: 'We have ordered a probe into this serious lapse of security. The Bureau of Civil Aviation Security (BCAS) is investigating.'

BCAS is the regulatory authority for civil aviation security in India.

The airline in a statement confirmed the incident and said the matter was immediately reported.

'Shortly after Kingfisher Airlines flight IT 4731 landed in Thiruvananthapuram and after all 27 guests on board had deplaned, a routine security check was being carried out. During this security check, an unclaimed package was found,' the airline said.

'The matter was immediately reported to the authorities, who have removed the package from the aircraft,' it added.