Fifty Shades of Grey author EL James has topped a list of the world's highest earning authors.

The British writer - who became a sales phenomenon last year - took an estimated $62 million, according to the data compiled by Forbes magazine.

A film adaptation of the first of her Fifty Shades erotica trilogy is expected next year for which she is believed to have pocketed more than $3 million for the rights, Sky News reports.

James Patterson, the author behind the Alex Cross novels, is second having generated almost $60 million in the survey, based on sales data, published information and details from industry sources for the year to June.