An Australian diplomat has fallen to his death from a Manhattan balcony after a night out with his wife and friends.

Julian Simpson, 30, died when he slipped over a railing at his Lower East Side apartment just after 1.40am, a New York Police Department spokesman confirmed to Fairfax Media.

He was Australia's second secretary to the United Nations and based in Australia's permanent mission to the United States in New York.

The NYPD spokesman said a group of about 10 people had gathered at Mr Simpson and his wife's apartment at 19 Clinton Street after a night out for dinner and drinks.