President Obama on Monday signed a landmark anti-smoking bill which he said will reduce the number of children who take up smoking and ultimately save American lives. 

The bill would give the federal government unprecedented authority to regulate tobacco. The law allows the regulatory Food and Drug Administration to reduce nicotine in tobacco products, ban candy flavorings and block labels such "low tar" and "light." Tobacco companies also will be required to cover their cartons with large graphic warnings. 

"Today ... the decades-long effort to protect our children from the harmful effects of tobacco has emerged victorious. Today change has come to Washington," Obama said. 

The law, called the Family Smoking Prevention and Tobacco Control Act, won't let the FDA ban nicotine or tobacco outright, but the agency will be able to regulate the contents of tobacco products, make public their ingredients and prohibit marketing campaigns, especially those geared toward children. 

"It is a law that will save American lives and make Americans healthy," Obama said, calling it a "victory for bipartisanship" as well as a victory for health care reform. 

The president said the legislation should reduce some of the billions the nation spends on treating tobacco-related illnesses, "the leading cause of preventable death in the United States." 

Anti-smoking advocates looked forward to the bill after years of attempts to tame an industry so fundamental to the U.S. that carved tobacco leaves adorn some parts of the Capitol. 

Opponents from tobacco-growing states argued that the FDA has proven through a series of food safety failures that it's not up to the job. They also said that instead of unrealistically trying to get smokers to quit or to prevent others from starting, lawmakers should ensure that people have other options, like smokeless tobacco. 

As president, George W. Bush opposed the legislation and threatened a veto after it passed the House last year. The Obama administration, by contrast, had issued a statement declaring strong support for the measure. 

Obama talked about his own struggles breaking a cigarette habit Monday, noting that he picked up smoking at an early age. 

"I know how difficult it can be to break this habit," Obama said. 

The Associated Press contributed to this report.