Online shopping is emerging as a new challenge to tobacco control, as more young people are using the Internet to circumvent age restrictions and purchase cigarettes.

Zhang Yunlong, a 16-year-old from Shenyang, Liaoning province, admitted he is a chain smoker.

"I've been smoking for more than two years and have been buying cigarettes online for one year," he said.

Zhang said it takes him only a few minutes to complete his online purchases.

"Owners of online stores don't care if you are an adult or adolescent. You only need to pay the money and they will deliver the cigarettes to you," Zhang said.

According to the Chinese Association for Tobacco Control, more than 20,000 vendors are selling cigarettes on Taobao.com, China's largest online shopping site.

Chinese law stipulates that those who produce or sell cigarettes need special licenses to do so. Most online stores skirt this regulation by claiming to be selling cigarette packaging.

"No one would believe that a cigarette package would cost more than 100 yuan ($16). Stores selling packaging are actually selling cigarettes," said an online vendor surnamed Lin.

A survey carried out by the association at 30 schools in Beijing and Henan province showed that four out of 10 middle-school students have purchased cigarettes.

More teenagers are buying cigarettes online not only to avoid questioning from their parents, but also because of their low prices. A carton of Chunghwa-brand cigarettes costs 980 yuan in most conventional stores, but can be purchased online for just 150 yuan.

Some of the low-priced cigarettes being sold online are recycled gifts or expired, while others are counterfeit, Lin said.

Zhang Li, director of the pulmonary health department of a hospital in Shenyang, said teenagers' bodies are not fully developed, meaning smoking can do more harm to their bodies.

Authorities have largely been unsuccessful in controlling tobacco in China.

With China's online population continuing to grow, it is likely that online tobacco sales will also increase in the future.

"Online cigarette sales are part of illegal tobacco trading and may cause tax revenues from legal cigarette sales to decrease. The national tobacco bureau should crack down on unlicensed online sales," said Yi Tianxiang, a lawyer from Tianjin.

"Refraining from selling cigarettes to young people is not just a slogan," said Yang Gonghuan, former deputy director of the Chinese Center for Disease Control and Prevention, adding that progress has yet to be made since a tobacco control plan was issued by authorities at the end of 2012.