Asylum seekers have been recruited by drug gangs to sell cocaine in Central's upmarket nightclub district, police say.
And they are even offering punters a free "line" of the drug that sells for HK$1,500 a gram to prove the quality of their product.
The dealers, who investigators say are from Africa, are selling cocaine mainly to expatriates every weekend on secluded Ezra Lane below Wyndham Street.
They are also to be found underneath the escalator near Hollywood Road.
They ply their trade from 4am to 8am between Friday and Sunday to catch clubbers either on their way to a venue or going home after a night out. As asylum seekers, they are not legally allowed to work.
But in the early hours of Saturday morning, the Sunday Morning Post found the dealers doing a brisk trade selling cocaine to the crowds of expatriates milling around Ezra Lane.
One dealer was charging HK$1,500 for a gram of cocaine. When asked if it was of good quality, he offered to give out a free "line" to prove it.
But after more questions, the suspicious dealer asked: "Are you a cop or what?"
Four or five other dealers were touting their wares as well, mostly standing in an alley way under the escalator at Hollywood Road.
Police are still unsure who exactly is supplying and organising them. Two years ago triad-linked criminal gangs were found to be using South Asians to sell drugs in the same way.
Some of the gang members involved in the old racket were asylum seekers. Some were criminal fugitives from their own countries and others were long-time Hong Kong residents.
A police source explained: "The difference is that the African dealers are much more subtle and not as obvious.
"The South Asian dealers just blatantly stopped people in the street in Central. But both groups specifically target expatriates."
It is generally hard for the police to make an arrest, as the suspects must be caught with the drugs on them.
The police source added: "We do search these dealers regularly and at random. But if they have no drugs on them, there's nothing we can do. We have to catch them in the act of selling."
The source also said recent arrests do not seem to have acted as a deterrent, with dealers soon back on the streets again.
Police said they would be continuing to carry out undercover operations, in which an officer will either buy drugs or will try to discover where the dealers are hiding their stash.
Official police figures show the number of arrests for drug offences last year was 5,371.