The BJP government in the state had in March this year requested the Centre to conduct a CBI probe into the attack following the demand from opposition Congress.
But the Centre declined, stating that the National Investigation Agency had already completed its investigation into the incident, a senior state official told PTI today.
The Maoists attacked 'Parivartan rally' of Congress in Jiram valley of Bastar on May 25, 2013. Several senior Congress leaders, including the state Congress president Nand Kumar Patel, Mahendra Karma and former Union Minister Vidyacharan Shukla, were killed in the attack.