Nearly 57 people, linked to the Popular Front of India (PFI), have been arrested in raids conducted by the police, Special Task force and Anti-Terrorist Squad.
The raids were held in various locations in 26 districts across Uttar Pradesh on Tuesday.
Additional Director General (law and order) Prashant Kumar said in a brief statement that the documents and other items seized during the raids were being scrutinized.
He said that legal action will be taken as investigations progress.