Kurt Derksen, 58, unlawfully left a B.C. psychiatric hospital earlier this week, and police say he could be in Ottawa. (Police handout)

Ottawa police are asking for the public's help to find a man who left a B.C. psychiatric hospital unlawfully, and who may now be in Ottawa.

Kurt Derksen, 58, was let out of the Colony Farm Forensic Psychiatric Hospital in Port Coquitlam to visit his brother in Richmond, B.C., on a day pass.

He left the residence and a Canada-wide warrant was issued. Police said they received information that he may be in Ottawa.

Derksen is described as a white man standing at about five feet nine inches tall. He weighs about 201 pounds and has short, brown hair and blue eyes. Derksen also has a full beard, and is possibly wearing glasses.

If spotted, police are asking the public not to approach the man, and instead call 911.

Neighbours have raised concerns about security at the hospital. In the last three years, 43 patients have failed to return on time while on day leave, and four attempted to escape. One patient is still at large after failing to return from a day pass in May.

The 190-bed facility, which has a maximum security wing, houses some of the most dangerous offenders in the province, sent there because the courts have found them not criminally responsible for their offences due to mental disorders.