it was published by Tom Miller on Beijing's Sanlitun bar area in the Shanghai Morning Post, and of course denied by the Beijing police, but the story spread like wildfire on the Chinese blogs and newspapers, expressing incredulity and outrage.
Follow up reports couldn't do much because Miller didn't state any sources and later claimed they wished to be anonymous... BUT there was a bar owner who said he was told to monitor Blacks and Mongolians (who fitted the description of local drug dealers apparently) and made to sign a stamped chop promising: "to keep to curfews, not allow the illegal sale of drugs, and refuse certain known customers."
Its interesting to note after all the hoo-ha Miller wrote another report (of another anonymous source) from a police officer denying a ban (and some say thus covering his backside up from his earlier mistake).
If you can read Chinese the official pledges signed in all the Sanlitun bars are pictured here. It's definitely not a ban on Blacks and Mongolians as Miller reported it was:
In the end there is no proof for the verbal story, and no proof against it, due to the lack of the source.
However there are two theories emerging:
1. Its true and the bar owners/ patrons and Beijing police are collectively covering it up, and are breaking the law
2. Miscommunication / translation: verbally "to monitor Blacks and Mongolians coming in the bar" and also an official pledge to "ban certain characters" being read as one and the same as to "ban all Blacks and Mongolians" in Millers report.
The source:
Shanghaiist: More on the Beijing bar ban confusion