'Although security officials routinely check all vehicles entering the governor's house, the fact that the explosives were hidden inside the back seat probably helped evade the security net.'

Meanwhile, the outlawed Kangleipak Communist Party (KCP), a rebel group fighting for an independent homeland for the Metei community of Manipur, claimed responsibility for planting the bomb. A KCP leader telephoned newspaper offices to own up the incident.

'We have heard about KCP's claim and the investigations are on,' Kailun said.

There are 19 separatist groups active in Manipur, which borders Myanmar, with demands ranging from secession to greater autonomy. Insurgent violence has claimed about 10,000 lives in the past two decades.