In the early hours of Tuesday, anti-narcotics police officers in Ngu Hanh Son District raided a karaoke parlor and found 47 party-goers showing signs of using banned drugs.

37 of them, 12 Vietnamese and 25 foreigners, tested positive for banned substances.

Police found the group had been using ketamine.

According to a police report, the karaoke bar had not opened officially, but still welcomed guests every day. The parlor is owned by a Chinese woman and her customers ordered drugs on social media, the report says.

Police are expanding the investigation into drug abuse in the central city.

Last year, 18 foreign tourists from Australia, Colombia, Malaysia, New Zealand, South Africa, the U.K. and the U.S. were held for smoking marijuana inside a bar in Da Nang.

Vietnamese police have recently intensified their crackdown on drug abuse at nightclubs and karaoke parlors across the country.

Drug use is strictly prohibited in the country and users are fined and taken to rehab centers. Producing or trading in drugs are criminal offenses that can face the death penalty.

Each year around 1,600 people die of drug overdose in Vietnam. Around $93.7 million is spent on buying drugs and $44.6 million on running rehab facilities, studies show.