English to Japanese Other Journalism

From https://blog.chrislkeller.com/aps-guidelines-for-off-the-rec...

In the (US) journalism context, a source who provides information on "deep background" cannot be referred to at all, even anonymously. The journalist instead presents the information without mentioning a source (as if it came from the journalist's own knowledge).

"Deep background" can be contrasted with information provided "on the record" - the source can be quoted by name - and information provided "on background," which means the quoted source's name is not published but a general description of their job position or familiarity with the events that are being reported on can be used. (An example of "on background" reporting would be referring to a source as a "senior government official.")

I'm looking for the Japanese phrasing that adequately conveys this "deep background" concept (which may or may not be a more literal translation). Thank you.