The number of drug-related crimes in which foreigners were involved has been on the rise in Shanghai in recent years with the number of expats growing, Shanghai municipal prosecuting agency said on Sunday.

Altogether, 45 expats were involved in such cases since the beginning of 2015. There were 14 cases in 2015, 19 last year and 12 so far this year, the Shanghai People’s Procuratorate said.

"Most of these expats were in the age group between 20 and 30 and were overseas students who studied in Shanghai," Gu Xiaomin, head of public prosecution against major and influential cases at the prosecuting agency.

Most of the suspects were involved in cases of trafficking small amounts of drugs and transporting drugs from overseas, he said.

"As most of them were drug addicts themselves, they relied on selling a small amount of drugs, usually less than 1 gram each time, to afford the expenditure on drugs. They didn’t sell drugs in order to earn high profits," Gu said.

These suspects came from 23 foreign countries, such as Australia, Canada, South Korea, Guinea and Ghana.

Antony Sichee Mo, a 22-year-old man from Australia, was recently sentenced to five months in prison by a Shanghai court for his conviction on charges of providing venues for drug users.

He provided his residence to at least five of his Chinese schoolmates to take drugs on multiple occasions from September to the end of last year, when he was then an international student at the School of Design at East China Normal University.

Gu said those convicted usually received month-long jail terms and were deported afterward.

The latest figures from the National Bureau of Statistics showed that 215,000 expats from 167 countries and regions are working in Shanghai, the largest foreign population in any Chinese city. There are another more than 70,000 overseas students in the city.

Data from the municipal prosecuting agency also showed that a total of more than 19,000 people from the Chinese mainland were prosecuted for drug-related crimes in Shanghai from 2012 to 2016, and the number of such cases decreased by around 10 percent year-on-year.

Part of the reason for the drop was that a rising number of suspects resorted to online social platforms for communication and payment so that it became harder to investigate such cases, said XuYanping, deputy head of the Shanghai People’s Procuratorate.

"Some of the suspects used the voice function in smartphone applications and deleted the records afterward to dodge police investigation," he said. "And some hid the drugs in express parcels."