The Belgian branch of the Church of Scientology has gone on trial and faces a possible ban for fraud and extortion, charges it claims are meant to ruin its reputation.

The case opened in a packed Brussels courtroom on Monday where the prosecution demanded that the church, known internationally for celebrity members including Tom Cruise and John Travolta, explain where it got its financing.

“The church’s revenues were roughly €5,000 [£3,500] a week; €2,000 came from the sale of books and videos and €3,000 from courses and training,” the Belga news agency quoted the group’s treasurer as saying.

The treasurer, who worked for the church until 2005, said she was not paid but was not required to pay the church’s fees, while her husband contributed about €10,000 for training.

The church sharply divides opinion – critics say it is cult and a scam, while supporters say it offers much-needed spiritual support in a fast-changing world.

The Belgian authorities launched an investigation in 1997 after several former members complained about its practices. A second inquiry followed in 2008 when an employment agency accused the church of making bogus job offers in an attempt to recruit new members.

As a result, 11 members of the Belgian branch, as well as two affiliated bodies, were charged with fraud, extortion, running a criminal organisation and violating the right to privacy. A conviction could lead to a ban.

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,” a spokesperson said on Friday.

Church of Scientology in Los Angeles, California. Photograph: Getty Images

“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.”

The Church of Scientology was founded in 1954 by the American science fiction writer L Ron Hubbard. It is recognised as a religion in the US and in some other countries such as Italy, Spain, the Netherlands and Sweden, and claims a worldwide membership of 12 million. The group’s headquarters are in Los Angeles.