Police officers have been ordered to avoid "flirting" and accepting alcohol from journalists.
Elizabeth Filkin, the former parliamentary commissioner for standards, warned of the "fraught issue" of drinking with reporters as she outlined a new framework for officers coming into contact with journalists.
In a guide issued at Scotland Yard, officers will also be urged to keep a note of any conversation they have with journalists, she said.
In her review of press-police relations in the wake of the phone-hacking inquiry, Ms Filkin said it was the view of many people that "information is deliberately leaked for various kinds of improper benefits".
She said drinking with officers "may be seen as inappropriate hospitality".
"Mixing the media with alcohol is not banned but should be an uncommon event," her report said.
She said there were "some very serious issues" relating to contact between journalists and police which "eroded trust from the public".
The report urges officers to "watch out" for "late-night carousing, long sessions, yet another bottle of wine at lunch - there are all long-standing media tactics to get you to spill the beans. Avoid."