A diffusion is a request for information or action directly from one NCB to another, or to the entire INTERPOL network. Diffusions are less formal than notices but can serve the same purpose, so a diffusion can request the arrest and detention of an individual just like a Red Notice. All diffusions are in INTERPOL’s information system.
The main difference between a Red Notice and a Diffusion is that the latter is circulated through but not ‘by’ INTERPOL: the issuing country acts directly in order to seek the arrest of an individual in another country, and does not need approval from the General Secretariat to do so.
Diffusions contain information similar to that set out in Red Notices, and are frequently disseminated whilst the issuing member country awaits formal Red Notice approval. They are subject to exactly the same rules on data processing as Red Notice and can be challenged and removed in the same way.