Millionaire financier Jeffrey Epstein has died in prison in New York in an apparent suicide while awaiting trial on sex trafficking charges.

The 66-year-old was found dead in his cell at the Manhattan Correctional Centre on Saturday morning, sources said, and the medical examiner's office confirmed his death.

He had pleaded not guilty to the allegations and would face up to 45 years in prison if convicted.

Epstein's arrest last month saw separate investigations launched into how authorities handled his case initially when similar charges were brought against him more than a decade ago.

In that case in 2008, a deal allowed Epstein to plead guilty to soliciting a minor for prostitution in Florida and avoid more serious federal charges.

Federal prosecutors in New York reopened the probe after investigative reporting by The Miami Herald stirred outrage over that plea bargain.

US Labour Secretary Alexander Acosta resigned last month after coming under fire for overseeing that deal when he was US attorney in Miami.

Epstein's lawyers maintained the new charges brought by federal prosecutors in New York were covered by the deal and were improper.

They said he has not had any illicit contact with underage girls since serving his 13-month sentence in Florida.

A little over two weeks ago, Epstein was found on the floor of his cell with bruises on his neck.

At the time, it was not clear whether the injuries were self-inflicted or from an assault.

PA Media