On the morning of Wednesday, July 6, the arrest was made under PACE in the Ipswich area.
The 45-year-old man was arrested for collecting terrorist information in violation of Section 58 of the Terrorism Act of 2000.
The man has been released on bail, and all address searches in the Ipswich area have been completed.
The investigation is linked to far-right ideology.
Detectives are collaborating with colleagues from the Eastern Region Special Operations Unit on the investigation.