A new study shows the dangers of cigarette warnings listed on packaging has little impact on teens, and will continue to smoke knowing the risks.

"Pictorial warnings work better than text alone, but if positioned on the back of the pack are less visible and less effective," researchers said in a new release.

The findings were published in the journal Tobacco Control.

Researchers collected data from more than 1,000 minors ages 11-16 in U.K., using a Youth Tobacco Policy Survey twice in 2008 (1401) and again in 2011 (1373).

"The teens were quizzed about the visibility and impact of the warnings; how well they served as visual cues; how easy they were to understand and believe; and how persuasive they were," according to the news release. "Their responses were scored on a sliding scale from 1 to 5.  Most of the respondents in both waves (68-75%) had never smoked; 17-22% had experimented with cigarettes; and around one in 10 were already regular smokers, defined as smoking at least one cigarette every week."

According to the researchers, more than half of their participants admitting to smoking "often" or "very often."  These youth said they notices the warnings and 1 out of 5 "looked closely at them."

"As warnings need to be salient to be effective, positioning pictorial warnings only on the less visible reverse panel limits their impact," write the authors. "While recall was high at both waves for pack-front warnings, it was low (below 10%) for the pictorial warnings on the pack reverse, fear-appeal pictures aside," the authors wrote.

The authors report the youth smokers noticing the warnings on the back of cigarette cartons dropped from 77% in 2008 to 66% in 2011.  Researchers believe using same warning images may be the U.K.'s key problem in curbing teen smokers.

"Positioning pictorial warnings only on the back of packs may have had a deterrent effect on never and experimental smokers, but for most measures no significant differences were observed. The impact on regular smokers was negligible," researchers conclude.