WASHINGTON - Food companies should revamp their marketing to children by advertising foods that are healthy, four US agencies said on Thursday in proposing voluntary principles for the food industry.

The proposed principles, which would turn children's food advertising on its head, calls for ads to be for foods that "make a meaningful contribution to a healthful diet" and minimize ingredients that could have a negative impact on weight and health.

The interagency working group is made up of the Federal Trade Commission, Centers for Disease Control and Prevention, Food and Drug Administration and US Department of Agriculture. It put together the proposal at the prompting of Congress.

If implemented, the principles would mean a revolution in food advertising to children, which is now dominated by ads for salty chips and sugary cereals, drinks and yogurt.

"The (FTC) commission is aware of the significant impact the proposal would have on the current marketplace. A significant percentage of the products currently marketed to children would not meet the proposed nutrition principles. Some foods would likely require substantial reformulation," the five FTC commissioners said in a statement.

Children were defined as being up to age 17, and the principles were to be implemented by 2016.