Suspecting a larger conspiracy behind the Goa blast in October, a central security agency has started a probe to track the perpetrators of the crime allegedly carried out by Hindu extremists.

After registering a case, the National Investigation Agency (NIA), established in the aftermath of last year's audacious Mumbai terror strikes, dispatched a team to Goa to get details of the blast in Margao area in which two people were killed, official sources said.

Right-wing Hindu group Sanathan Sanstha's involvement in the blast has been suspected but the organisation has refuted the charge. This is the first ever case related to a Hindu group that has been handed over to the agency.

The Sanstha, which is now headquartered in the temple town of Ramnathi in the Ponda region of Goa, has members and associates in several states. "Investigations have indicated that the Sanatan Sanstha may have had its base in Maharashtra before moving to Goa," the sources said.