Coca-Cola Co and its largest independent bottler, Coca-Cola Enterprises Inc, are teaming up on an ad campaign against a possible U.S. tax on soft drinks, according to the Atlanta Journal Constitution.

The two Atlanta-based companies will launch a print and digital campaign in seven key U.S. markets including Washington, D.C., New York, Los Angeles, Chicago and Boston, the newspaper said on Tuesday on its website.

There have been increasingly vocal calls for taxes on sugary drinks and junk food to help fight the problem of obesity in the United States.

Since Congress will ultimately decide whether a tax is imposed, the newspaper said the campaign is expected to include political publications and websites in Washington, D.C.

A strongly worded report on child obesity released earlier this month recommended that state and local governments tax junk food and soft drinks, while the American Heart Association said people should limit their sugar intake and said soft drinks were the No. 1 source of added sugars in the American diet.

Citing an interview with Coke Enterprises Chief Executive John Brock, the Atlanta paper said the penny-per-ounce tax that has been suggested would increase the cost of a 12-pack of soda by $1.44. Brock called that mind-boggling, the paper said.

Officials at Coke and Coke Enterprises were not immediately available to comment.

(Reporting by Martinne Geller, editing by Dave Zimmerman)