The Belgian branch of the Church of Scientology has gone on trial accused of fraud and extortion and faces a ban if convicted.
The case opened in a packed Brussels courtroom where the prosecution demanded that the church, known internationally for superstar members such as Tom Cruise and John Travolta, explain where it got its financing.
The Belgian authorities launched a first investigation in 1997 after several former members complained about its practices.
A second investigation followed in 2008 when an employment agency charged that the church had made bogus job offers so as to draw in and recruit new members.
The court heard on Monday that members would pay €2,000 (£1,400) for a ten-day “purification” programme, comprised of sauna sessions, running, sleeping, healthy eating and food supplements.
The authorities as a result charged 11 members of the Belgian branch, plus two affiliated bodies, with fraud, extortion, running a criminal organisation and violating the right to privacy.
Last week, the church said it had "no doubt" it would be cleared.
"The Church of Scientology goes to court with the firm intention of seeing the fundamental rights of its Belgian members finally recognised," it said in a statement on Friday.
"Not only does the Church contest the charges against it, which affect the fundamental rights of all Scientologists, it also intends to denounce the serious judicial abuses (against it) of the past 18 years," it said.
Headquartered in Los Angeles, the Church of Scientology was founded in 1954 by American science fiction writer L Ron Hubbard.
It is recognised as a religion in the United States and claims a worldwide membership of 12 million. It was described as a sinister cult by a British judge.