Use of snuff and chewing tobacco by U.S. adolescent boys, particularly in rural areas, has surged this decade, a federal agency said in a report on Thursday that raised concern among tobacco control advocates.

The use of such smokeless tobacco products increases the risk of oral cancer as well as heart disease and stroke. It leads to nicotine addiction just like cigarette smoking.

The report by the U.S. Substance Abuse and Mental Health Services Administration showed a 30 percent increase in the rate of smokeless tobacco use among boys aged 12 to 17 from 2002 to 2007. Use by adults remained stable.

In 2007, the report estimated that 566,000 boys in that age group had used chewing tobacco or snuff.

"This trend toward more smokeless tobacco use by kids is of great concern," Danny McGoldrick, vice president for research at the Campaign for Tobacco-Free Kids advocacy group, said in a telephone interview.

"This is an industry that has a history of targeting kids because they know that's when everybody starts," he added.

Among adolescent boys, the rate of use of smokeless tobacco rose from 3.4 percent in 2002 to 4.4 percent in 2007, according to the report.

McGoldrick said the increase occurred as smokeless tobacco companies greatly increased their spending on marketing and introduced a new range of products.

The findings reiterated the need for the U.S. Food and Drug Administration to have the power to regulate tobacco products, as legislation being considered by U.S. lawmakers would do, McGoldrick said.

Use of smokeless tobacco products was most common in rural areas, particularly in the South and Midwest, SAMHSA statistician Jim Colliver said in a telephone interview.

The findings were based on government surveys in which about 68,000 people nationwide were questioned annually. Among health and substance use questions, they were asked whether they had used snuff or chewing tobacco in the previous month.

An estimated 7.8 million Americans overall used smokeless tobacco during 2007, according to the report. Men were about 15 times more likely to use it than women.

More than half of the adolescent smokeless tobacco users also were current cigarette smokers, and the figure jumped to two-thirds in ages 18 to 25, according to the report.