Thiruvananthapuram, March 21 (IANS) It was a narrow escape for 27 passengers of a Kingfisher flight from Bangalore when explosive were found in the cargo hold after they had deplaned at the airport here.

'It is not a bomb but certainly one which is explosive in nature. We have decided to register an FIR (first information report) and investigations have begun. We expect that by tomorrow (Monday), we will know what kind of explosive it is,' Thiruvananthapuram police chief M.R. Ajith Kumar said.

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

The security officials quickly cordoned off the aircraft.

'We are investigating how this happened. Certainly this is a security lapse. The explosive is now with experts,' Kumar said.

The Kingfisher flight returned back to Bangalore in the afternoon after a thorough security check, he added.

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.'

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