"From initial report it seems to be a well organised attack which the Central and state intelligence agencies failed and could not find out," CPI said after the national executive meeting.
CPI has asked the NIA and other investigating agencies to conduct thorough time-bound investigation and bring the real culprits to book.
"These cowardly attacks once again highlight the urgent need to strengthen intelligence against terror attacks," CPI(M) Polit Bureau said in a statement here.