A woman who recently defected from the Church of Scientology has claimed that she was held against her will and forced to spend almost 12 years touring the Caribbean on a cruise ship owned by the organisation.

Valeska Paris told a TV interviewer that she was 18 when she joined the crew of the Freewinds, a vessel the Church describes as its floating "cathedral" and which once hosted Tom Cruise's birthday party. She alleged that her passport was confiscated, and that, until she was 24, she was prevented from setting foot on dry land without an escort.

The claims were aired by ABC news in Australia, where she currently lives. They have been strongly denied by the Church, who say Ms Paris boarded the ship of her own free will and was perfectly free to leave.

Her troubled relationship with the organisation spans three continents and several decades. Born in Switzerland, to parents who were both involved in Scientology, she moved to the UK at the age of six, and spent her formative years at the Church's headquarters in Sussex.

After turning 14, Ms Paris graduated from the organisation's youth wing, the "Cadet Org" to its senior volunteer wing, the "Sea Org". She signed a contract agreeing to remain a member for the ensuing period of no less than one billion years. Trouble began, she now claims, when her mother defected from Scientology in 1995, and began denouncing it on French television. Ms Paris says church elders then ordered her to "disconnect" from her parent.

A year later, when she was 18, Ms Paris joined the crew of the Freewinds. "I was sent to the ship for two weeks," she told ABC, adding that for a salary of $50 a week, she was often required to work long shifts in the vessel's engine room.

"It's hot, it's extremely loud, it's smelly, it's not nice," she said. "I was sent down there at first for 48 hours straight on almost no sleep and I had to work by myself... I did not want to be there, I made it clear I did not want to be there."

Among the landmark events of her time on board was the 2004 birthday party of the actor Tom Cruise. In a second interview, with the Village Voice newspaper, Ms Paris recalled helping to decorate the ship, but claims she "wasn't allowed" to attend, because she was suffering from a cold sore.

Video of the ensuing celebration later leaked to YouTube shows Cruise performing the song "Old Time Rock and Roll".

Ms Paris left the Freewinds in 2007, and moved to a church facility in Sydney with her husband, the former Australian rugby league star Chris Guider. They eventually decided to defect from the church and now have a young son.

The Church meanwhile denies that it ever holds anyone against their will. In a two-page statement, it described the Freewinds as a "wonderful place", saying Ms Paris was free to leave at any time and made numerous unaccompanied trips to dry land.