The office of Canada's auditor general lost 120 USB drives, or one in five entrusted to staff last year, possibly containing sensitive information, a local newspaper reported Thursday.

The daily Toronto Star cited a September 22 internal security memo lamenting a "lack of accountability" for the lost drives.

The opposition New Democratic Party called the revelation "troubling," but the auditor general's spokesman Ghislain Desjardins told AFP the risk of a data breach was low.

"All USB keys are encrypted and password protected," he explained.

The memo said the drives may have contained identifying information about individuals or institutions but nothing secret or classified.

The auditor general has since moved to using a secure file transfer (secure FTP) site to exchange information with outside institutions and has recalled all other USB devices, except for those currently being used in audits.