Jeffrey Epstein sexually exploited dozens of underage teens, some as young as 14. (File)

An autopsy on disgraced financier Jeffrey Epstein, who was found dead in his jail cell, has concluded that he committed suicide by hanging, US media reported Friday.

The ruling, first reported by The New York Times, comes six days after the 66-year-old, who was accused of trafficking girls as young as 14 for sex, was found dead.

The newspaper said the official results of the New York city medical examiner's investigation into how Epstein had died showed that the wealthy hedge fund manager had killed himself.

It cited officials as saying that Epstein had used a bedsheet to hang himself.

The report came a day after US media reported that preliminary findings from the post-mortem examination had found broken bones in Epstein's neck.

The Washington Post and The New York Times cited sources familiar with the autopsy report as saying Epstein had broken the hyoid bone near his Adam's apple.

Epstein, a multi-millionaire who counted Britain's Prince Andrew and Donald Trump as friends, was charged with one count of sex trafficking of minors and one count of conspiracy to commit sex trafficking of minors.

According to prosecutors, Epstein sexually exploited dozens of teenagers at his homes in Manhattan and Florida between 2002 and 2005.

He denied the charges but faced up to 45 years in jail if found guilty.

The FBI and Justice Department are investigating how America's most high-profile inmate managed to take his own life just weeks after an earlier reported suicide attempt.

The warden of the Metropolitan Correctional Center where Epstein was housed has been temporarily reassigned and two guards put on administrative leave pending an investigation.

They guards were reportedly asleep when they should have been checking on Epstein.

Epstein's death came a day after a court released documents in which an alleged victim said he used her as a "sex slave" and that she was forced to have sex with well-known politicians and businessmen.

Prosecutors have pledged to pursue cases against anyone else involved in Epstein's alleged crimes.