When it comes to new rules for marketing so-called light cigarettes, tobacco companies plan to honor the letter of the law—but to shade the truth, critics say.

Come June, under the new federal tobacco law, cigarette companies will no longer be allowed to use words like “;light”; or “;mild”; on packages to imply that some cigarettes are safer than others.

But in a move that critics say simply skirts the new rules, tobacco companies plan to use packaging to make those same distinctions: light colors for light cigarettes.

So Marlboro Lights, the nation's best-selling brand, from Philip Morris, will be renamed Marlboro Gold, according to a flier the company recently sent to distributors. Likewise, Marlboro Ultra Lights will morph into Marlboro Silver.

And anticipating the new rules, R.J. Reynolds has already changed Salem Ultra Lights, which are sold in a silver box, to Silver Box.

“;They're circumventing the law,”; said Gregory N. Connolly, a professor at the Harvard School of Public Health. “;They're using color coding to perpetuate one of the biggest public health myths into the next century.”;

The National Cancer Institute says there are no health benefits from light cigarettes and that they may be more dangerous because some people inhale them more deeply than regular cigarettes.

The Food and Drug Administration has begun a federal review of the color-coding approach—a step that could conceivably lead to further actions against products designated as light.

The law taking effect this summer does not bar companies from making light cigarettes, only from using words like “;light”; in marketing. The industry says that it is complying and that it should be free to use colors on its packages to market different product lines to adult consumers.

“;Colors are really used to identify and differentiate different brand packs,”; David M. Sylvia, a spokesman for Altria, the parent company of Philip Morris, said Thursday. “;We do not use colors to communicate whether one product is less harmful or more harmful than another.”;

In a letter to the FDA on Thursday, James E. Dillard III, a senior vice president of Altria, said banning certain colors would be unconstitutional under commercial speech and property protections.

The tobacco regulation passed last year gave the FDA sweeping new regulatory authority over tobacco. One new requirement is that companies must prove to the FDA that a product is safer than conventional cigarettes before it can be marketed as such.

While Congress specifically banned some terms, including “;low”; and “;mild”;—present on about half the packages of cigarettes sold in the United States—it also gave the FDA authority to act against “;similar descriptors”; that could mislead consumers to think certain products were less risky.

Last month, the agency published a notice that it could take action against colors like silver or pastels, as well as additional words like “;silver,”; “;smooth”; and “;natural,”; which some companies are still planning to use on cigarette packages. The notice sought public and industry comments, which are due Friday.

Kathleen Quinn, a spokeswoman for the new FDA Center for Tobacco Products, said Thursday that the agency would “;thoroughly review”; the use of color on cigarette packages by June 22, the effective date of the wording ban and the first anniversary of the law's passage.

As it happens, Friday is also the deadline for petitions to be filed with the Supreme Court asking it to hear appeals from the 2006 conviction of tobacco makers for racketeering in making fraudulent claims about light cigarettes.According to Connolly of Harvard, the tobacco industry has known for at least a decade from World Health Organization actions that words like “;light”; would eventually have to come off the boxes, giving it time to prepare the other visual cues on packaging.

He shared with The New York Times a set of marketing material about the new color system that he said had been given to him by people working in the tobacco industry.

The color coding, Connolly said, is red and dark green for regular and menthol; blue, gold and light green for light cigarettes; and silver and orange for ultra lights.

“;The myth of safer cigarettes is perpetuated,”; Connolly said. “;Light cigarettes unleashed a monster.”;

But rather than fight over shading and coloring on the packages, he urged the FDA, using its new authority, to regulate filters and ingredients in those cigarettes to make them taste harsher.

Light cigarettes have a different taste because they are filtered differently and may contain additives, Connolly said. Studies have shown that people who smoke light cigarettes satisfy their nicotine cravings by inhaling the smoke more deeply, smoking more cigarettes and taking more puffs on each cigarette.

Altria said it had used terms like “;light”; as well as packaging colors to connote different tastes, not safety. But study after study—including ones by the industry disclosed in tobacco lawsuits—has shown consumers believe the terms and colors connote a safer product.

Moreover, adults believe cigarette packs with the terms “;smooth,”; “;silver”; or “;gold”; are also easier to quit than other ones, and teenagers said they were more likely to try them, according to a survey and study published in September in the European Journal of Public Health.

The survey authors, led by David Hammond, a health studies professor at the University of Waterloo in Ontario, called for plain, uncolored packaging.

Matthew L. Myers, president of the Campaign for Tobacco-Free Kids, a Washington advocacy group, said cigarette companies had responded to bans of terms like “;light”; and “;low tar”; in at least 78 countries by color-coding their packaging to convey the same ideas.

“;If the FDA concludes that either new wording or color coding is misleading consumers,”; he said, “;then the FDA has authority to take corrective action.”;