The administration of New York City Mayor Michael Bloomberg, along with City Council Speaker Christine Quinn, a leading mayoral candidate, announced legislation Monday to make New York the strictest major city in America when it comes to regulating smoking.

The minimum age to buy cigarettes and other tobacco products within the five boroughs would rise from 18 to 21, but Bloomberg and  fellow advocates of the bill emphasized that it would not make it illegal for people between the ages of 18 and 21 to possess or smoke tobacco products.

Bloomberg has made expansive health reforms a centerpiece of his three terms in the city's highest office, banning smoking in public places like parks and beaches, banning trans-fats, requiring restaurants to display nutrition information and more.

But many of his proposals have been controversial, as best illustrated by the recent fight over his plan to ban the sale of sodas and other sugary beverages in amounts greater than 16 ounces. The policy was blocked from going into law by an alliance of libertarians, the soda lobby and groups that consider Bloomberg to be running a "nanny state" that intrudes too far into the lives of its citizens, but that didn't stop Bloomberg from bringing forth this newest effort to curb smoking.

The proposal was announced by Dr. Thomas A. Farley, the city health commissioner, and Quinn -- who is a leading candidate in the race to replace Bloomberg when his third term comes to a close.

“With this legislation, we’ll be targeting the age group at which the overwhelming majority of smokers start,” Quinn said at a news conference to announce the initiative, from which Bloomberg was conspicuously absent, delegating Farley to represent his administration.