ATLANTA (Reuters) - American kids are eating far too much salt, mostly from processed foods sold in stores, putting them at risk for high blood pressure and heart disease later in life, federal health officials said on Tuesday.

A report from the U.S. Centers for Disease Control and Prevention found that more than 90 percent of American children ages 6 to 18 consume too much sodium daily.

Those children eat an average of about 3,300 mg of sodium daily even before salt is added at the table, according to the CDC study based on national surveys in 2009 and 2010. That exceeds dietary guidelines calling for less than 2,300 mg per day.

The CDC noted that one in six young Americans already has elevated blood pressure - a condition closely linked to high sodium intake and obesity that can lead to heart attack and stroke.

The report found that 43 percent of the sodium came from 10 popular types of foods, including pizza, sandwiches like cheeseburgers, cold cuts and cured meats, pasta with sauce, cheese, salty snacks like potato chips, chicken nuggets and patties, tacos and burritos, bread and soup.

"Most sodium is from processed and restaurant food, not the salt shaker," CDC Director Tom Frieden said in a statement. "Reducing sodium intake will help our children avoid tragic and expensive health problems."

Dinner was the largest single source of sodium, accounting for nearly 40 percent of the daily intake, the study found.

The report said 65 percent of the sodium intake came from foods purchased in stores, with most of the sodium already in the products when purchased. Fast food restaurants including pizza places accounted for another 13 percent, the CDC said.

Meals offered at school accounted for 9 percent of total sodium consumption.

Teenagers ate more sodium than younger children, according to the study that drew from interviews with more than 2,000 school-aged children.

The study found a need to reduce sodium "across multiple foods, venues and eating occasions," the CDC researchers said. In particular, processed foods should have less sodium, the researchers said, citing efforts in Britain that reduced total sodium consumption by 15 percent over seven years.

By David Beasley

(Editing by Letitia Stein and Will Dunham)