Actress Allison Mack is now in the authorities' sights over her alleged role as a recruiter for a sex cult following the arrest of co-founder Keith Raniere, according to one report.

Mack, who played Clark Kent's love interest Chloe Sullivan in CW series Smallville , has been allegedly named a co-conspirator in the case, the group's former publicist Frank Parlato has claimed .

Mack, 34, will reportedly face sex trafficking charges after allegedly working alongside former co-star, Emmy Award-winning actress Kristin Kreuk to recruit other women into the NXIVM cult.

Allison Mack attends Amazon Studios' premiere for "Lost In Oz" at NeueHouse Los Angeles in August last year. (Getty) (Getty)

"Allison was used, as was Kristen, as a lure to bring in other women because of their celebrity status," the NY Post has quoted Parlato as saying.

According to the complaint, Raniere — known within the group as "Vanguard" — oversaw a barbaric system in which women were told the best way to advance was to become a "slave" overseen by "masters".

They also were expected to have sex with Raniere and do menial chores for masters, and to keep the arrangement a secret or be publicly humiliated, the complaint says.

Co-founder Raniere was arrested in Mexico last Monday and fronted court in Fort Worth, Texas the following day on charges filed by federal prosecutors in Brooklyn.

Parlato reportedly claims Mack started as a slave for the group before eventually becoming a "slave master".

"Her nickname among defectors is ‘Pimp Mack'," Parlato was reported as saying.

In a letter attributed to Raniere previously posted on a website related to NXIVM, the leader of the self-described self-help group leader denied sanctioning the notorious practices.

"These allegations are most disturbing to me as non-violence is one of my most important values," the letter said.

The complaint said that many victims participated in videotaped ceremonies where they were branded in their pelvic area with a symbol featuring Raniere's initials.

"During the branding ceremonies, slaves were required to be fully naked, and the master would order one slave to film while the other held down the slave being branded," the complaint says.

Mack, 34, allegedly worked alongside former co-star Kristin Kreuk to recruit other women into the cult. (Getty) (Getty)

Investigators said Raniere preferred exceptionally thin women, so "slaves" had to stick to very low-calorie diets and document every food they ate.

As punishment for not following orders, women were forced to attend classes where they were made "to wear fake cow udders over their breasts while people called them derogatory names", or threatened with being put in cages, court papers say.

Raniere left the United States late last year after The New York Times reported the stories of some women who defected from their secret sorority and the government began interviewing potential witnesses.

Alleged cult co-founder Keith Raniere. (Youtube/Keith Raniere Conversations) (Youtube/Keith Raniere Conversations)

A photo of the brand allegedly used on women in the NXIVM cult. (Supplied)

He sought to cover this trail by using encrypted email and ditching his phone, court papers say.

Raniere was ultimately found staying with several women in a luxury gated community in Puerta Vallarta where villas can run US$10,000 (A$13,015) a week to rent, investigators say. After authorities took him into custody on a US warrant, investigators said the women got into a high-speed car chase.

The website related to the group describes Raniere as a "scientist, mathematician, philosopher, entrepreneur, educator, inventor and author" who has "devoted his life to studying the human psychodynamic and developing new tools for human empowerment, expression and ethics".

Raniere and NXIVM have been the subject of criticism for years, dating back to at least 2012 when the Times Union of Albany published a series of articles examining the organisation and allegations that it was like a cult.

Authorities also say Raniere has been bankrolled by Clare Bronfman, an heiress to the Seagram's liquor fortune.

Bronfman gave millions of dollars covering expenses like private air travel costing US$65,000 (A$84,617) flight, court papers say.