Calgary psychiatrist Dr. Aubrey Levin now faces 21 charges of sexual assault, based on allegations by patients. (CBC)A Calgary psychiatrist who had been facing a single charge of sexual assault against a patient now faces 20 additional counts, police said Friday.

Dr. Aubrey Levin, 71, was first charged in March after one of his long-term patients came forward with an allegation.

The Calgary police sex crimes unit was subsequently approached by 20 former patients, who claimed Levin assaulted them during counselling sessions or court-ordered visits.

Levin regularly worked with justice officials on criminal cases, evaluating defendants and providing expert testimony in court.

It's alleged that assaults took place in Levin's office or in examination rooms at the Peter Lougheed Centre, police said.

Levin appeared in provincial court Friday morning. He was allowed to remain free on bail under several conditions. He must:

• Not have contact with alleged victims.
• Not practise medicine of any kind.
• Appear at court when requested.
• Surrender his passport and remain in Canada, except with written permission from the court.

Levin was suspended by the College of Physicians and Surgeons in March. He came to Canada in the 1990s from South Africa, where he had worked as a psychiatrist for the military during the apartheid era.