Mayor Michael Bloomberg yesterday signed a law restricting the sale of cigarettes to people younger than 21.

Increasing the age on cigarette purchases, he said, "will prevent young people from experimenting with tobacco when they are most likely to become addicted."

Bloomberg has crusaded against cigarettes throughout his 12 years in office, first banning smoking from bars and restaurants. The city also extended the smoking prohibition to parks and beaches. The new law also extends to electronic cigarettes.

Council Speaker Christine Quinn said New York City is the first major city to increase the smoking age and hopes other places will follow their lead.

"This legislation marks a major step forward in reducing youth smoking rates with the potential to spare thousands of New Yorkers from a lifetime of nicotine addiction and health problems," she said in a joint statement with Queens Councilman James Gennaro.

Bloomberg also signed legislation that aims to curb cigarette-tax evasion by letting the city Department of Finance lock up stores of repeat offenders and bans the use of coupons for cigarette purchases.