The raid at 1:15 a.m. found one man, 28-year-old Dang Van Ny, in possession of 54 pills suspected to be ecstasy and nine packets containing white powder suspected to be ketamine, police said.

They took 67 customers to a police station and 58 of them tested positive for banned substances.

Police said they would either be fined or put in rehab centers.

Da Nang, considered the third most important city in Vietnam after Hanoi and HCMC, is a popular travel destination.

The city has seen several drug busts in recent months, especially in karaoke parlors, dance floors and other entertainment sites. Last month, a karaoke parlor in the city was busted with 32 customers using drugs.

Synthetic drug users account for 86 percent of all drug addicts in Vietnam, according to official data.

Vietnamese authorities deal with around 20,000 cases involving drugs every year and arrest around 30,000 people. The country has some 250,000 registered addicts, but the actual figures are thought to be much higher.

After local and international criticism of an approach based on treating drug addiction as a "social evil" to be dealt with by forced abstinence and re-education, the government began a program in 2013 to gradually replace compulsory detention centers with community-based, voluntary treatment regimens.

Around $44.6 million is spent on running rehab facilities in Vietnam every year.