A Jiangsu IT engineer has been detained for three days for selling Virtual Private Network (VPN) services as China cracks down on online cross-border operations without approval.

Police busted the suspect, surnamed Zhao, who claimed to work in an Internet company as a software developer, on August 21, Xinhua News Agency reported.

Zhao, from Nanjing, capital of East China's Jiangsu Province, confessed that at the very beginning, he set up a VPN account to help himself read overseas information. Smelling a business opportunity, he decided to sell VPN services for profit.

Zhao said since June he had sold the service at 10 yuan ($1.50) for a month, 50 yuan for six months, 90 yuan for a year and 120 yuan for two years without government approval. Police said that he amassed a total 1,080 yuan, according to the Xinhua report.

Based on China's Cyber Security Law, which came into effect on June 1, Nanjing police detained Zhao for three days and confiscated all his illegal income.

Zhao's case is not isolated. According to a court document posted on the official website of the Supreme People's Court in March, Deng Jiewei, a 26-year-old man from Dongguan, Guangdong Province, was sentenced to nine months' jail with an additional 5,000 yuan fine for providing software and tools to invade and illegally control the computer information system.

The document said that Deng had been selling two VPNs via his website since October 2015 which allowed Internet users to visit foreign websites that could not be accessed in the Chinese mainland. He and his partner made nearly 14,000 yuan selling the software.

According to a January regulation issued by the Ministry of Industry and Information Technology, all basic telecommunication firms and Internet access service providers are barred from setting up or renting special lines including VPNs to carry out cross-border operations, unless authorities grant them an approval.

Global Times