An unfinished draft of a new novel by Sex And The City author Candace Bushnell has been leaked online by a hacker.

The prankster, who goes by the name Guccifer, has released 50 pages of Bushnell's manuscript after breaking into her email account and obtaining a message the writer sent to her publisher.

In the email, Bushnell writes that she is "having a great deal of fun" working on her latest project, which is tentatively titled Killing Monica.

The book appears to centre around a middle-aged woman named Pandy, who begins the story by spilling her divorce problems to a friendly New York City cab driver.

A spokesperson for publisher Hachette's Grand Central Publishing confirmed to Reuters the pages posted to the Internet were written by Bushnell.