Fashion executive Peter Nygard on Monday made a brief appearance in a Toronto court for the first of several trials on charges for sexual assaults that spanned decades in Canada and the United States.

Jury selection was set for next week, followed by the prosecution's presentation of evidence starting on September 26.

Held in prison since his arrest in December 2020, the 82-year-old Finnish-Canadian is being tried in Canada's largest city for alleged sexual assaults and forcible confinement involving several people between 1987 and 2006.

He faces similar charges in Quebec and Manitoba, as well as extradition to the United States, where he has been accused of raping dozens of women and girls, racketeering and trafficking.

Through his lawyers, Nygard, known for his long, flowing gray hair and flamboyant dress sense, has denied all of the accusations.

Reports from the Toronto courtroom described him arriving in a wheelchair, looking frail.

At the time the Toronto charges were laid in October 2021, Nygard was already fighting a US extradition request. Months later Quebec police would lay charges too, followed by Manitoba in July.

In the United States, dozens of women and girls from disadvantaged economic backgrounds or who had histories of abuse have accused him of grooming and luring them to his luxury estates on the pretence of lucrative modelling opportunities.

Those alleged crimes, according to the US indictment, took place between 1990 and 2020. Nygard and his accomplices, including employees of his group, "used force, fraud, and coercion to cause women and minors to have sex" with them, it said.

Nygard, the founder of women's clothing company Nygard International, has long boasted about his rise from humble beginnings, as a young immigrant who built a fashion empire with nearly 170 stores at its peak.

His company, however, filed for bankruptcy shortly after the FBI and police raided Nygard's Manhattan corporate headquarters in 2020. According to US court documents, company funds were said to have been used to host dinner parties, poker games and so-called "pamper parties" where minor girls were drugged and women assaulted if they did not comply with his sexual demands.

Partygoers were often photographed and their personal information, including weight and physical measurements, were kept in a registry. Nygard also paid from corporate accounts for victims' travel, living expenses, plastic surgery, abortions and child support, said American prosecutors.