FORMER Smallville star Allison Mack has sat in a New York court alongside alleged cult leader Keith Raniere as a judge set their trial for October 1.

ABC reports that assistant US Attorney Moira Penza indicated in the Brooklyn court that more arrests are expected.

She also stated in court that they anticipate additional charges for both defendants.

Mack, who played Clark Kent’s pal Chloe Sullivan in the Smallville TV series, is charged with recruiting women and grooming them for sex with Raniere as part of a group known as NXIVM. She is facing sex trafficking, sex trafficking conspiracy and forced labour conspiracy charges.

She’s out on $US5 million bail, while Raniere has been refused bail.

Raniere pitched NXIVM as a self-improvement program for the stars with Battlestar Galactica’s Nicki Clyne, Dynasty star Catherine Oxenberg’s daughter, India, and Mack’s former Smallville co-star, Kristin Kreuk, all members at one time.

Mack reportedly tried to lure singer Kelly Clarkson and actress Emma Watson into the fold.

Raniere had pleaded not guilty on all three charges.

Mack, 35, is reportedly considering a plea deal.

Mack’s lawyer, Sean Buckley, asked that her next court appearance be waived, but judge Nicholas Garaufis refused the request, chiding, “People have to show up. This is a very serious matter.”

Raniere is accused of running twisted workshops on the NXIVM (pronounced Nexium) compound, about 32 kilometres outside of Albany, New York which taught women about “the need for men to have multiple sexual partners and the need for women to be monogamous.”

Mack allegedly recruited the women on the pretext that the cult was a “women’s empowerment group” and groomed them to have sex with Raniere.

Both face 15 years to life in prison if convicted of the charges.