As many as 600 former patients at a maximum-security psychiatric hospital are moving ahead with a class-action lawsuit alleging abuse, despite the institution's attempts to block a controversial Swiss report that lawyers say is key to the case.

The report, from a Swiss psychiatrist and ethics expert, concludes the Philippe-Pinel Institute broke basic ethical guidelines and treated the former patients inhumanely when they stayed at the institute.

The hospital sought an injunction against the report's publication, arguing it reflects European standards that aren't binding in Quebec, and could be damaging to the institution's reputation.

A press conference scheduled Tuesday, when the report was to be made public, was cancelled because of the threat of the injunction.

A judge ruled against the hospital's request late in the day.

A former patient launched the lawsuit after he was hospitalized at Pinel in 2001. Hospital employees labelled him as violent, and they allegedly mistreated him during his transfer to another hospital.

The former patient claims he was shackled and strip searched like a criminal, even though he hadn't been charged with any offence, said Ian-Kristian Ladouceur, a lawyer representing the plaintiffs.

As many as 600 other former patients claimed to have been subjected to similar treatment during stays that spanned a four-year period between 1999 and 2002, Ladouceur said.

"One of the practices was isolation over a period of 20 days. The second alleged damage is being frisked, searched with their pants down. And they were frequently handcuffed when they were transferred."

When the patient who initiated the suit was released from hospital, he consulted a mental health advocacy group.

The class-action suit he filed was accepted by the Quebec court in 2003. The claims have not been proven in a court of law.

Expert opinions were sought, explained Ladouceur, and Montreal psychiatrists urged the legal team to consult with the Swiss psychiatrist, who wrote a report that characterized the patients' treatment as excessive and unreasonably controlling.

Despite the injunction, the class action will proceed, Ladouceur said, and court proceedings are expected to start within the year.