Jeffrey Epstein, the disgraced American financier charged with child sex trafficking, took his secrets to the grave after apparently hanging himself in a prison cell while awaiting trial.

The FBI launched an investigation into the death as a row erupted over how Epstein was allowed to cheat justice, as victims expressed anger at being denied their day in court.

Epstein's death meant the full story of the powerful political figures and celebrities potentially connected to his alleged sex ring may never be told.

His lawyers initially refused to rule out foul play, fueling conspiracy theories that his death will silence further damaging revelations.

Epstein, 66, died the day after a tranche of documents were released in a civil case in which Virginia Giuffre, who claimed to have been his teen "sex slave," had sued Ghislaine Maxwell, 57, Epstein's former girlfriend, for defamation.

Mrs Giuffre, now 35, had claimed to have had sex with the Duke of York when she was 17. The duke has always categorically denied the allegations, which were struck from court record in 2015 after being described as "immaterial and impertinent" by the judge.

Epstein was found unresponsive in his cell at the Metropolitan Correctional Center in Manhattan at 6.30am on Saturday. It was "an apparent suicide", the US department of justice said.