Financier Jeffrey Epstein died by suicide while awaiting trial on sex-trafficking charges in New York, a former law enforcement official said. Picture: AP/Richard Drew

Washington - The apparent suicide of disgraced financier and convicted sex offender Jeffrey Epstein on Saturday prompted demands for answers and a flood of unfounded conspiracy theories, one of which even US President Donald Trump seemingly endorsed.

Epstein, 66, was found unresponsive in his prison cell in New York at about 6:30 am (1030 GMT), according to the Metropolitan Correctional Center.

His death followed the publication on Friday of a cache of documents that provided more extensive details on how his alleged sex-trafficking network operated between 2002 and 2005.

New York Mayor Bill de Blasio told reporters the death was "way too convenient."

"What a lot of us want to know is, what did he know?" de Blasio told reporters in Iowa. "How many other millionaires and billionaires were part of the illegal activities that he was engaged in?"

Earlier, de Blasio tweeted: "Some of wealthiest people in the world committed a horrible crime. If they think for a second that they got away with it because Jeffrey Epstein is dead, they're dead WRONG."

Democratic Congresswoman Alexandria Ocasio-Cortez tweeted: "We need answers. Lots of them."

Trump, who was spending the weekend at his golf club in New Jersey, shared a post from comedian Terrence Williams that made unsubstantiated claims about Clinton being linked to Epstein's death.

He also shared a tweet from an unverified account that said "top Democrats, including Bill Clinton, took private trips to Jeffrey Epstein's 'pedophilia island.'"

Epstein was indicted last month on charges of sex trafficking of minors and conspiracy. He had pleaded not guilty and was denied bail three weeks ago.