The Food and Drug Administration announced Tuesday that for the first time it had begun exercising its power to regulate cigarettes and other tobacco products, an authority it was given under a 2009 law supported by President Obama.

Agency officials said they had authorized the sale of two new products — both of them Newport cigarettes made by Lorillard Tobacco — and rejected four others. The law forbade them to name the rejected products, they said.

Before the law, cigarettes were manufactured without any federal regulation.

Instead, states decided where and how tobacco products would be sold, but had no authority over the ingredients they contained.

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Now, the FDA is deciding which new products can be sold.

In addition to cigarettes, the agency’s authority covers loose rolling tobacco, chewing tobacco and snuff.

The agency can reject cigarettes and other tobacco products that its scientists believe pose public-health risks above and beyond comparable products already on the market, a sharp departure from past practice, when tobacco companies could change existing products and introduce new ones at will.

Advocates said the FDA’s use of this authority was a milestone.

“This is the first time in history that a federal agency has told tobacco companies that they could not market a new or modified cigarette because of the public-health problems they pose,” said Matthew Myers, president of the Campaign for Tobacco-Free Kids, an advocacy group.

Dr. Margaret Hamburg, the FDA commissioner, called the development “historic” and said that the FDA was the only agency in the world that possessed such powers.

Under the law, the agency can also limit ingredients, such as nicotine, in tobacco products.

Still, the tobacco industry has scored some recent successes against federal regulators.

An attempt to require companies to put graphic images on their labels, another power granted by the 2009 law, has been challenged in court, so far successfully.

Regulators in other countries, including Australia and Uruguay, have so far prevailed against the industry in requiring such images.

Mitchell Zeller, director of the Center for Tobacco Products at the agency, said some of the rejected products presented new public-health risks by including, for example, more added chemicals than a similar product currently being sold.

Some products were rejected because their makers had not provided enough information.

Researchers said that it remained to be seen how effective the agency would be over time in the face of the industry’s formidable legal firepower.