The governing body of the American Medical Association voted yesterday to oppose all tobacco advertising and to seek national legislation prohibiting it.

The vote by the AMA's 371-member House of Delegates at its semiannual meeting here puts the nation's most influential medical organization in the forefront of a growing movement to ban cigarette advertising from the print media and from outdoor billboards, as it was banned from broadcasting in 1971.

Tobacco industry spokesmen immediately criticized the proposed ban as violating freedom of speech.

The near-unanimous vote by the policy-setting House of Delegates to seek a legal ban on tobacco advertising reflects a mood within the 271,000-member medical organization that educational campaigns and voluntary measures have not done enough to curb smoking.

"The reason this route is being taken now reflects the frustrations physicians have felt for a long time," said Dr. Robert E. McAfee, a Portland, Maine, surgeon and member of the AMA's House of Delegates. "It's the number one health problem in this country."

Only one doctor, D.E. Ward of the North Carolina delegation, spoke against the resolution, saying it violated tobacco manufacturers' "constitutional right to advertise their products in a competitive manner."

Several of his colleagues agreed that the AMA's decision to pursue a legislative ban on tobacco advertising raised constitutional questions, but said it was worth a court battle.

"We expect a challenge," said Kirk Johnson, the AMA's general counsel. "We are willing to fight it."

The tobacco industry spends over $2 billion a year on advertising in the print media, on billboards and on various promotional events, such as tennis tournaments. The resolution to oppose tobacco promotion applies to all forms of advertising.

Included in the ban would be smokeless tobacco products such as chewing tobacco and snuff, whose promotion is currently less strictly regulated than that of cigarettes.

Dr. Ronald Davis, a Centers for Disease Control physician in the AMA House of Delegates, said the AMA's next move will be to draft a sample bill to be considered by the body, possibly at a meeting next February. Once a bill is approved, the AMA will seek a congressional sponsor, he said.

The organization's aim in seeking a ban on advertising is to "reduce the enticement of young people to smoking," said Dr. John Dawson, another AMA delegate. "What you do as a responsible adult is your own problem," he added.

Tobacco industry officials claim cigarette advertising does not persuade people to start smoking, but only induces smokers to try different brands.

Bans on advertising in some European countries have not reduced consumption, and U.S. cigarette consumption rose during the decade after advertising was banned on radio and television, according to Anne Browder, a spokeswoman for the Tobacco Institute.

In a letter to the AMA, the American Newspaper Publishers' Association and the Magazine Publishers' Association said, "Products that can be legally sold in our society are entitled to be advertised; if it is legal to sell a product it should be legal to advertise it."

After passing the antiadvertising resolution, the House of Delegates also voted in favor of a 21-year minimum age for buying tobacco products; for a ban on vending-machine cigarette sales; and for required health warning labels on smokeless tobacco products.