SHENZHEN - Police in South China's Guangdong province on early Sunday morning detained 50 foreign drug users at a party in the city of Shenzhen.

The public security bureau of the city's Nanshan District received reports of drug-taking at an overpass culvert. Among the 491 people taken away for investigation, 118 tested positive for drugs, mostly marijuana. Police later placed 93 people, including 50 foreign nationals, in administrative detention for a maximum of 15 days.

Police also detained two suspected drug dealers, both foreign nationals, on criminal charges.

"Foreigners accounted for over half of the detainees, which suggests a serious problem of drug use among foreigners in Shenzhen," said a police officer who declined to be named.

The culvert, nicknamed "IKEA Bridge Culvert" due to its proximity to an IKEA mall, is known for regular parties held by foreigners.