Foreign teachers detained in east China's drug-using case come from EF, an English language training provider. (Photo: IC)

Police in east China's Jiangsu Province cracked down a drug-using case and arrested 19 people, including 16 foreigners.

According to police in the city of Xuzhou on Wednesday, the detainees included seven foreign teachers employed by an education agency. Nine others were foreign students.

All 19 people involved in the case failed drug test, and the case is under further investigation, said the public security bureau of Xuzhou city.

EF Education First (EF), an English language training provider, said in a statement published on its official Weibo account Wednesday that it was deeply regretful that some teachers of its Xuzhou branch were involved in the drug-related incident during non-work time.

The company said it will immediately terminate employment contracts with employees once they were confirmed to have possessed or used narcotics in China.

EF is an international education company that entered China in 1994. It provides educational programs including English courses for both children and adults.