A clinic in Ottawa may have infected 6,800 patients with HIV and hepatitis over a 10-year period after health inspectors learned that its doctor had lapses in cleaning medical instruments.

Dr. Isra Levy, the city's medical officer of health, did not disclose the name of the clinic but said its patients dating back 10 years ago will be informed through a letter to be sent out Monday that they may have been infected with Hepatitis B and C virus and HIV, which causes AIDS.

The chances of infection with hepatitis B is one in one million, one in 50 million with hepatitis C and less than one in three billion with HIV, according to Levy.

Former patients should start getting letters Tuesday so they can undergo blood test if they are concerned, Levy said in a press conference on Saturday, according to Canada.com.

The letter indicates the telephone number of an Ottawa Public Health call center that will open on Tuesday to answer questions from the 6,800 patients.

The lapses of the clinic and its physician were discovered during an inspection of the facility by the Ontario College of Physicians and Surgeons in June. The Ottawa Public Health then started tracing the addresses of former patients, who include non-Ontario residents. The list of the former patients was completed only on Thursday.