In a major breakthrough, the National Investigation Agency (NIA) has arrested a key conspirator in Bengaluru's Rameshwaram Cafe blast case, according to an official statement issued on Thursday.

Muzammil Shareef was picked up on Wednesday and placed in custody as a co-conspirator after NIA teams cracked down at 18 locations, including 12 in Karnataka, five in Tamil Nadu and one in Uttar Pradesh, it said.