TORONTO - Ontario's privacy commissioner is ordering Durham Region's health officer to ensure medical data is encrypted on portable devices.

The order follows an incident in December when the health data of more than 83,000 people who received H1N1 flu shots went missing.

A nurse was taking a USB key containing the records to her car in Whitby, Ont., to take it to a clinic site when the device was lost.

Commissioner Ann Cavoukian says she also expects all health data stored on mobile devices in Ontario to include strong encryption.

She says despite the availability of encryption to prevent breaches, unencrypted mobile devices continued to be used.

"This is both distressing and completely unacceptable," Cavoukian said in a statement early Thursday.

Cavoukian also asked that the Ministry of Health to ensure all 36 health units in Ontario review their procedures with regard to mobile device encryption.