THE Church of Scientology and seven of its French leaders went on trial on Monday on charges of organised fraud that could lead to an outright ban on the organisation in France.

Known for its Hollywood celebrity followers Tom Cruise and John Travolta, the Church is in the dock in Paris for the second time in six years, although French courts have prosecuted several individual Scientologists since 1978.

The Paris court was hearing the complaint of a woman who alleges she was manipulated into handing over 20,000 euros $A28,000 for costly Scientology products, such as an "electrometer'' to measure mental energy.

The woman said she was approached in a Paris street by a Scientologist in late 1998 who offered a free personality test, at a time when she was feeling psychologically fragile.

After being told that her test results were poor, the woman was sold a series of "life-improvement courses'', vitamins and other costly products that landed her into debt.

A second complaint before the court came from a woman who alleged that she was forced by her Scientologist employer to undergo testing and enrol in courses. In the end, she was fired.

French defence lawyers argue that Scientology resorts to harassment and pressure to rein in victims who all show signs of vulnerability.

The Scientology Celebrity Centre in Paris, its director Alain Rosenberg and six other top officials are accused of preying on vulnerable would-be followers "with the goal of seizing their fortune by exerting a psychological hold,'' they said.