The authorities receiving the report shall keep confidential the relevant information of the informant, and protect the legitimate rights and interests of the informant.

接受举报的机关应当对举报人的相关信息予以保密，保护举报人的合法权益。

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Now that often is shorthand for trying to protect an informant, but at the time nobody really suspected that the agent was going to turn out as Mr. Donaldson.

NPR: Irish Spy May Hurt N. Ireland Peace Process

By July, Det Supt Baxter had no choice but to investigate claims by a Garda Detective Sergeant John White that shortly before Omagh, Det Ch Supt Jennings knew republican dissidents were looking for a car to steal for a "spectacular" in Northern Ireland but ordered that it be allowed to cross the border to protect a Gardai informant.

BBC: Cross border co-operation was a myth