Keith Raniere, a United States man accused of running a cult-like group in which women were kept on starvation diets, branded with his initials and ordered to have sex with him, has been found guilty of all charges against him by a New York jury.

Key points: Raniere headed the "self-help" group Nxivm (pronounced "nexium")

Raniere headed the "self-help" group Nxivm (pronounced "nexium") He created a secret sorority to blackmail and enslave women

He created a secret sorority to blackmail and enslave women Smallville actor Allison Mack and alcohol heir Clare Bronfman pleaded guilty in the case

The verdict on Wednesday (local time) comes after a trial that lasted more than six weeks.

Raniere, 58, was charged with crimes including racketeering conspiracy, sex trafficking and possession of child pornography.

Sex cult leader Keith Raniere, centre, was found guilty of all charges. ( AP: Elizabeth Williams )

He faces a possible sentence of life in prison. His sentencing is set for September 25.

Raniere is the founder of Nxivm (pronounced "nexium"), a purported self-improvement organisation.

Prosecutors said he created a secret sorority within Nxivm called DOS in which female "slaves" turned over compromising materials that were used to blackmail them.

The case implicated two high-profile women — Smallville actor Allison Mack and Clare Bronfman, heir to a Canadian alcohol fortune. Both have pleaded guilty in the sensational case.

DOS was sold to recruits as an all-female organisation, when in fact it was controlled by Raniere, according to former members who testified at the trial.

Outside of the courthouse, after the verdict was read, a group of former Nxivm members gave the prosecution team a round of applause.

Catherine Oxenberg, the mother of a former cult member, called her daughter in front of reporters to tell her the verdict.

"I'm so happy," the mother was heard saying.

Smallville actor Allison Mack pleaded guilty to blackmailing two women as part of the sex trafficking ring. ( Reuters: Shannon Stapleton )

Inner circle of slaves

Raniere was the "grandmaster" of an inner circle of slaves, who in turn recruited slaves of their own.

Some of those recruits were coerced into having sex with Raniere, and some were branded with his initials, according to former members.

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DOS slaves were forced to hand over nude photos and embarrassing confessions and were told the material would be released if they disobeyed orders or tried to leave, according to a former member and other witnesses.

Raniere, pictured in April last year, kept female "slaves" by blackmailing them with compromising photos. ( AP: Elizabeth Williams, file )

Prosecutors also said that, years before creating DOS, Raniere began a sexual relationship with a 15-year-old girl.

The child pornography charges stem from explicit pictures he took of the girl, who went on to become one of his inner circle of DOS slaves.

Raniere's lawyer, Marc Agnifilo, told jurors in his closing arguments on Monday that no women were ever forced to do anything against their will.

Other members of Nxivm were charged alongside Raniere, and have all pleaded guilty.

They included Nxivm president Nancy Salzman; her daughter Lauren Salzman, who testified as the prosecution's star witness; actor Allison Mack; and Seagram liquor heir Clare Bronfman.

Seagram heir Clare Bronfman pleaded guilty to fraud and harbouring someone in the US without pay. ( AP: Mark Lennihan )

The group first became known for its "executive success program" courses, which purported to give students the ability to achieve their life goals by overcoming mental blocks.

Witnesses testified that leaders of the organisation psychologically manipulated and abused its members and demanded total obedience.

Reuters