WASHINGTON, US (Reuters) - Schools that serve more fruits, vegetables and whole grains to pupils should see higher federal support rates than those serving less-healthier meals loaded with high fats and sugar, Agriculture Secretary Tom Vilsack said on Tuesday.

Child nutrition programs, which include school lunch and breakfast, are due for an overhaul but Congress is not expected to act before 2010. The government has targeted improving the nutritional quality and access to school meals amid rising child obesity rates.

"It is important for us to reward top performers," Vilsack told the Senate Agriculture Committee. "We would encourage this committee and the Congress to take a look at reimbursement rates that would be linked directly to increased nutritional values."

He did not suggest how large the bonus should be. Schools get US$2.88  (S$4) in cash and Agriculture Department-provided food for each lunch meal served for free to poor children this school year.

School meal programs provide an estimated 40 million meals daily and more than half the student's food intake during the school day. Students can receive free or subsidized meals if their family's income is low enough.

Some $16.9 billion was allotted for child nutrition in the fiscal year that opened on Oct. 1, up $1.9 million from fiscal 2008.

Obesity rates among U.S. children have doubled in the last 20 years, and almost a third of American children are either overweight or obese. The epidemic of obesity is linked to a host of health problems such as heart disease and diabetes.

Senate Agriculture Committee Chairwoman Blanche Lincoln told Vilsack she was willing to pay more to serve healthier foods.

"I'm certainly sympathetic to the concept of higher reimbursement rates. Common sense does tell us that as we improve that quality it also increases the cost," she said.

Officials at the USDA are updating the nutrition and meal requirements used for school meals. The framework, last updated in 1995, sets standards that must be met by school programs to qualify for cash reimbursements and food from the government.

A report from the Institute of Medicine, an arm of the National Academies, recommended last month children should get more fruits, vegetables and whole grains in their school meals.

USDA oversees the contents of school lunches and bars the sale of foods with minimal nutritional value, such as soda, in the lunchroom. It does not control food sold in a la carte lines or school stores.

Vilsack and lawmakers on the committee said more attention must be paid to the nutritional content of these other venues.

"The concern is that we can do everything we need to do on the school lunch line and it could be counteracted by what we do or what we don't do in reference to vending machines and things that are sold in the school during the school day," he said.