An edgy ad campaign aimed at getting kids to stop smoking could be forced off the air because tobacco companies are refusing to keep footing the bill.

Former top federal health officials gathered to urge the companies to keep paying for the “truth” ad campaign run by the Washington-based American Legacy Foundation.

“I say to the tobacco executives, look if your words aren’t just rhetoric, then fund the truth campaign,” said Joseph Califano Jr., who served as former President Carter’s health secretary and is heading a petition drive to push cigarette makers to keep paying for the ads.

Tobacco companies agreed to fund the ad campaign in 1998 when the industry reached a $206 billion legal settlement with the states. But the agreement said if the companies participating in the settlement saw their market share drop below 99 percent after March 2003, those companies wouldn’t have to pay for the ads anymore.

That happened recently as small manufacturers, who aren’t part of the settlement, gained new customers. Morgan Stanley tobacco analyst David Adelman estimates those companies now have about 5 percent of the cigarette market.

The industry has so far given the American Legacy Foundation $1.5 billion to pay for the truth ads, which often showcase teenagers. In one, teens are seen dragging body bags in front of a cigarette company’s office. The teens are holding posters stating that 1,200 people die each day from tobacco-related diseases.

Lorillard Tobacco Co. has filed suit against the American Legacy Foundation, saying the ads have vilified the company. Lorillard points to one radio ad in which a person identifying himself as a dog walker phones the company and tells the operator he wants to sell the company “quality dog urine” because it is “full of urea,” one of the “chemicals you guys put into cigarettes.”

Lorillard, of Greensboro, N.C., has said urea is found naturally in tobacco leaves.

Company spokesman Steve Watson said his company does not plan to fund the ads now that it has no legal obligation to do so. “We have no intention of aiding them in their misguided mission to vilify tobacco companies,” Watson said.

Philip Morris USA issued a statement saying it had lived up to its commitment and touting the $125 million the company says it spends annually on anti-smoking and health initiatives.

But anti-smoking advocates say the companies’ ads aren’t effective. “There’s no way that you can rely on them and their ads to discourage teen smoking,” Califano said.

An estimated 2,000 young people become smokers each day, according to the American Legacy Foundation.

Cheryl Healton, head of the foundation, says it costs about $100 million annually to run the national ad campaign. Healton said if the companies refuse to pay for the ads, the foundation will have to decide whether to put itself out of business by spending down its $800 million endowment to continue the campaign.