THIRUVANANTHAPURAM, India (Reuters) - Explosive material was found in a package on a passenger plane after it landed in southern India, but it was not attached to a detonator and could not have exploded, officials said on Sunday.

The package, which was the size of a cricket ball and wrapped in a local newspaper, was found in a bag inside the cargo hold of an aircraft after all 27 passengers had disembarked.

The plane, belonging to Indian carrier Kingfisher Airlines, was moved to an isolated area in Thiruvananthapuram airport in the state of Kerala, having flown in from the IT and services hub Bangalore.

“It is a serious security lapse,” said U.K. Bansal, the special secretary for internal security in the home ministry. “As far as we know, there was no detonator and there was no timing device, so the bomb could not have gone off by itself.”

“Nevertheless it’s an explosive ... which is a very serious matter. So we will have to look at the type of security precautions which are put in place at our airports,” he added.

India remains jittery about the threat of militant attacks. A blast in the western city of Pune killed 16 people last month, the first major militant strike since the 2008 Mumbai attacks.

The home ministry had recommended extra security measures for Indian airlines after intelligence on a threat from militants to hijack a plane in January ahead of the country’s Republic Day.

Ajith Kumar, the police commissioner of Thiruvananthapuram, suggested the explosives might have been placed in the hold after the plane landed.

“The police will investigate whether the explosive material was placed in the aircraft at Thiruvananthapuram airport,” he said, adding police were questioning airport officials.