Sea Org, a youth group where the highest levels of Scientology are taught, has been described as a "boot camp" by former Scientology members and has been criticised for its military-style regimes.

Other former members have claimed the floating camp, which is partially based on ships, only teaches a Scientology belief-system and does not include a proper education.

The 33-year-old actress, who stepped out for the first time on Monday since filing for divorce, is thought to have argued with Cruise about their daughter's indoctrination into Scientology in the run-up to the split, particularly with regard to Suri becoming a member of Sea Org, according to the celebrity website TMZ.

Eventually she decided to separate from the Top Gun actor as the only way to stop Suri being sent away to the ultra-zealous organisation, the report said.

Cruise, who is said to be a big fan of the sect, reportedly has many close associates within the high-level Scientology group, including prominent Scientologist Jessica Feshbach. She was appointed as Holmes's chaperone in 2005 when the couple first met.

The Dawson's Creek star, who was raised a Catholic, was pictured smiling at photographers in New York on Monday as she emerged for the first time since news of the split surfaced in the media last week. The actress's Cartier diamond-studded wedding ring was notably absent.

The actress is also said to have returned to her pre-marriage publicist Leslie Sloane as well as firing her husband's security team, who have been guarding her.

The Church of Scientology denied that Sea Org was part of the reason for the couple's split, saying nobody under the age of 16 is allowed to join.

A statement released to TMZ said: "[Minors must have] consent of both parents and/or all legal guardians."

A lawyer for the church added: "There are no exceptions to that policy".