Assam police has arrested 15 persons directly involved in the serial blast that rocked the North-Eastern state on Oct 30.

Master minds behind the blast also have been identified, said Assam Chief Minister Tarun Gogoi.

"The main brains or sources behind the blasts here are suspected to be based in Bangladesh," he said.

"We have been able to identify all those directly involved in the blasts, barring for the explosion at Kokrajhar," the CM added.

Nine serial blasts rocked Assam on Oct 30 killing more than 85 people and injuring other hundreds.  

"We have arrested 15 of the blast suspects so far, although the brains behind the explosions who planned or financed could be in Bangladesh. We are in touch with the central government to help us in tracking them," Gogoi said.

"We have already put on high alert our police and paramilitary forces to prevent such attacks," he said.