Growing reports indicates that unrestricted marketing has its effects in increased number of young smokers in US. E-cigarette use is soaring among teenagers mainly because of advertisements aimed at their age group.

Seven out of 10 middle school and high school students say they have seen e-cigarette ads in stores, online or in other media, according to a new report from the U.S. Centres for Disease Control and Prevention.

According to the "Vital Signs" report published online Jan. 5 in the CDC's Morbidity and Mortality Weekly Report, more than 13 percent of high school students were using e-cigarettes in 2014 -- more than the number smoking regular cigarettes, and up from 1.5 percent from three years earlier. In middle schools, nearly 4 percent of students were using e-cigarettes by 2014. Meanwhile, spending on e-cigarette advertising jumped from $6.4 million in 2011 to about $115 million in 2014, the study authors noted.

The investigators found that about 69 percent of middle and high school students see e-cigarettes ads from one or more media sources. More than half see ads in retail stores, while about 40 percent see them online. About 36 percent see the ads on TV or at the movies, and around 30 percent spot them in newspapers and magazines.

Currently, e-cigarettes are not regulated in the United States, although the U.S. Food and Drug Administration has said it intends to regulate them.