NEW YORK — New York City retailers would be required to keep tobacco products out of sight under a first-in-the-nation proposal aimed at reducing the youth smoking rate, Mayor Michael Bloomberg said Monday.

The legislation would require stores to keep tobacco products in cabinets, drawers, under the counter, behind a curtain or in other concealed spots. They could only be visible during restocking or when an adult is making a purchase.

Bloomberg said similar prohibitions on displays have been enacted in other countries, including Iceland, Canada, England and Ireland.

“Such displays suggest that smoking is a normal activity,” Bloomberg said. “And they invite young people to experiment with tobacco.”

Stores devoted primarily to the sale of tobacco products would be exempt from the display ban.

The mayor’s office said retail stores could still advertise tobacco products under the legislation.

“We have made tremendous strides in combating smoking in New York City but this leading killer still threatens the health of our children,” said Dr. Thomas A. Farley, the health commissioner.

Farley said the city’s comprehensive anti-smoking program cut adult smoking rates by nearly a third – from 21.5 percent in 2002 to 14.8 percent in 2011 – but the youth rate has remained flat, at 8.5 percent, since 2007.

Smoking remains the leading preventable cause of death among New Yorkers, Farley said.

An industry group said the proposal was too much.

“It’s an over-the-top attempt to control the sale of a legal product,” said Andy Kerstein, president of the National Association of Tobacco Outlets, a trade group that represents about 20,000 tobacco stores, convenience stores and other stores that sell tobacco. “As Bloomberg has shown you, it is not going to stop with tobacco. What’s the next thing he’s going to do, size portions on steaks?”

The tobacco proposal is just the latest public health measure Bloomberg has backed, including pressuring restaurants to use less salt, adding calorie counts to menus and banning some large sizes of sugary drinks.

Jennifer Bailey, smoking as she waited for a bus on 34th Street, was no fan of the proposed tobacco restrictions or Bloomberg’s other public health initiatives. “It’s like New York has become a mini-Russia, a dictatorship,” she said.