BEIJING, May 31 -- As China toughens up on tobacco control, the country's teenagers are still finding it hard to resist the appeal of cigarettes.

As the world's largest tobacco producer and consumer, China has more than 300 million smokers, almost the size of the U.S. population. Another 740 million people are exposed to second-hand smoke.

Lax enforcement of the ban on tobacco sales to minors and marketing gimmicks targeted at teenagers ensure a steady increase in the smoking population.

The average age when youth begin to smoke in China has dropped to 10.7 years old. In the nation's capital, Beijing, where authorities have just introduced the toughest smoking ban to date, teenagers begin smoking at an average age of 12 to 13, according to a study by Peking University.

Around 6.4 percent of Chinese students between the ages of 13 and 15 have smoked cigarettes. The percentage is 10 percent among male students. Of teenagers who smoke, more than 80 percent tried their first cigarette before 13, according to a 2014 report by the Chinese Center for Disease Control and Prevention based on a survey of 155,000 students in 1,020 schools across 31 provinces.

While Beijing's new ban, effective on June 1, prohibits smoking in all the city's indoor public places, workplaces, and on public transportation, teenagers in the city are still exposed to cigarettes sold near their schools.

Chinese law bans the sale of tobacco and alcohol to minors, and local regulations generally prohibit cigarette sales within 100 meters of schools.

However, these bans are weakly observed and enforced, with cigarette vendors dotted around schools. Studies have found cigarette retailers seldom refuse tobacco sales to teenagers.

From mom-and-pop stores to stalls, cigarettes are displayed alongside snacks, stationery and toys to increase their appeal among teenagers. Some vendors even sell individual cigarettes as some students cannot afford whole packs.

A study by the disease control and prevention center of Beijing's Chaoyang District found that of the 87 middle schools in Beijing, two thirds are within 100 meters of cigarette vendors. Only 38 percent of cigarette peddlers near schools hang signs banning sales to minors and 81 percent failed to decline sales to investigators dressed in school uniform.

In southwest China's Yunnan Province, a separate study conducted by local NGO Pioneers for Health Consultancy Center found 88 percent of schools in downtown Kunming, the provincial capital, had tobacco retailers within 100 meters. Some retailers were situated less than 50 meters from schools.

Eighty-nine percent of students interviewed by the NGO said they have no trouble buying cigarettes from these retailers.

China sees nearly 1.4 million smoking-related deaths each year, more than those caused by AIDS, tuberculosis and traffic accidents combined, according to China's health authorities.

Yet despite campaigns to discourage teenagers from smoking, few students have thorough knowledge about the harm tobacco causes to health, and education efforts have been undermined by marketing campaigns targeting young smokers.

Hongta Group, one of the country's major tobacco producers, has a new cigarette brand called Yuxi 8090. The name hints at a younger generation of smokers born in the 1980s and 90s.

According its ad campaign, the 8090 line targets "the young and the energetic."

Tobacco sales have been on the rise. More than 50.99 million cartons of cigarettes were sold in China last year, a 37-percent rise from a year earlier.

While Chinese authorities have increased taxes on tobacco, currently at around 43.4 percent, that rate is still among the lowest in the world. Taxes of 61 percent are imposed in Japan, 64 percent in Singapore and more than 70 percent in Myanmar, Thailand and India.

China has signed the Framework Convention on Tobacco Control by the World Health Organization, effective since January 2006. According to the convention, members recognize that pricing and taxation are effective tools in reducing smoking across the population, especially teenagers.

But for now, it seems, cigarettes have not been taxed out of reach for China's youngest smokers.