WASHINGTON – After decades of reminding people about the dangers of cigarettes, offering nicotine gum or patches and making smokers huddle outside, the government is turning to gruesome pictures.

Federal health officials unveiled plans Wednesday to replace the warnings that cigarette packs began carrying 25 years ago with new versions using images that could include emaciated cancer patients, diseased organs and corpses.

Public health authorities and anti-smoking advocates hailed the move as a milestone in the battle against tobacco in the United States, which began in 1964 when the surgeon general first declared cigarettes a public health threat. That battle made steady progress for decades, but has been stymied in recent years, with a stubborn one in five adults and teens still smoking.

Tobacco remains the leading cause of premature and preventable death in the country, causing 443,000 deaths each year and about one-third of all cancer deaths.

Armed with new powers approved by Congress last year, the Food and Drug Administration is proposing warnings that include one containing an image of a man smoking through a tracheotomy hole in his throat; another depicting a body with a large scar running down the chest; and another showing a man who appears to be suffering a heart attack.

Others have images of a corpse in a coffin and one with a toe tag in a morgue, diseased lungs and mouths, and a mother blowing smoke into a baby’s face.

The new warnings will cover half the front and back of each pack and 20 percent of each large ad.

The FDA will gather public comment on 36 proposed images until Jan. 9 and select nine by June 22 after reviewing the scientific literature, the public comments and a study involving 18,000 people.

Beginning Oct. 22, 2012, any cigarette makers that do not put the new warnings on their packaging will not be allowed to sell their brands in the United States.

The move was praised by public health and anti-tobacco advocates, although some said they wished the warnings included other elements, such as a toll-free number to call to help people quit.

“In implementing the new warnings, the United States is catching up to scientific best practices,” said Matthew Myers of the Campaign for Tobacco-Free Kids.

Others, however, criticized federal officials for not going further, such as by banning smoking in more places.

R.J. Reynolds Tobacco, which is suing the federal government over tobacco regulation, said it was reviewing the proposed new warnings.

“It is worth noting that the legality of requiring larger and graphic warnings is part of our lawsuit,” said David Howard, an R.J. Reynolds spokesman.

But Philip Morris USA, which has supported FDA regulation, said the company “has actively participated in the FDA’s rulemaking and public comment processes and plans to do the same on this proposal.”

At least 30 other countries already require graphic warnings, including some, like Brazil, that often go even further than the proposed U.S. messages. Canada, which became the first country to require more graphic warnings in 2000, has seen a significant drop in smoking.

“It’s always difficult to point to a particular policy and say it’s due to that,” said David Hammond, a researcher at the University of Waterloo in Ontario who worked with the advertising agency that developed the candidate warnings for the FDA. “But all the evidence does point to the fact that these things do help.”The bottom line is that there’s no magic bullet,” Hammond said. “But about one-third of smokers say this increases their motivation to quit, and about the same proportion of former smokers say they remind them why they quit.”

Hammond and others warned, however, that within a year or two smokers become inured to the images, which will make it crucial that they be changed to remain effective.