Helen Gurley Brown, the editor-in-chief of Cosmopolitan magazine and author of Sex and the Single Girl, has died at 90, magazine publisher Hearst says.

Brown died in New York shortly after being admitted to hospital.

Hired by Hearst to turn around Cosmopolitan three years after her 1962 best-selling book, she edited the magazine for 32 years.

Under her, the magazine became famous for encouraging women to have sex, regardless of marital status.

Brown said her aim was to tell readers "how to get everything out of life - the money, recognition, success, men, prestige, authority, dignity - whatever she is looking at through the glass her nose is pressed against".

New York Mayor Michael Bloomberg paid tribute to Brown, saying that New York City had lost "a pioneer who reshaped not only the entire media industry, but the nation's culture".

"She was a role model for the millions of women whose private thoughts, wonders and dreams she addressed so brilliantly in print. She was a quintessential New Yorker: never afraid to speak her mind and always full of advice."

Brown was born in Arkansas on 18 February 1922, and moved to Los Angeles after her father died.

She graduated top of her class at John H Francis Polytechnic High School in 1939 before working as a secretary at various advertising agencies.

When finally given the chance to write advertising copy, she began winning prizes and became the highest-paid advertising woman on the west coast.

She was married at age 37 to former Cosmopolitan managing editor and movie producer David Brown, who encouraged her to write the book that became Sex and the Single Girl.