The National Investigation Agency (NIA) has registered a case in the Rameshwaram Cafe blast case.

After the Union Home Ministry issued direction in this regard, the NIA registered the case on Sunday evening.

The Central Crime Branch is, however, the primary investigation agency in the blast case.

The police have intensified the investigation by forming eight teams after the bomb went off on Friday at the cafe.

The Congress government in the state is confident of nabbing the bomber who spent nine minutes at the cafe before setting a timer for the low-intensity IED to explode, in which 10 persons were injured.

So far, no arrests have been made. However, the police released some persons who were detained for interrogation after finding no leads to nab the bomber.

Karnataka Chief Minister Siddaramaiah has directed the police to heighten the security in the state.

Home Minister Dr G Parameshwara said one of the reasons for the blast could be business rivalry. Other reasons could be upcoming Lok Sabha elections and creating fear among investors due to the stable government in the state, he said.

"As many investors are coming here given a stable government, this might have been done either to stop investors from coming to Bengaluru or due to some other unknown reasons," he said.

(With UNI inputs)