Elections Ontario has discovered a privacy breach that involves the personal information of voters in up to 24 provincial ridings.

CBC News has learned that memory sticks containing personal information about voters have gone missing from the office of the chief electoral officer for Ontario.

The information on the missing memory sticks includes the full name, address, gender and birth date of voters and may also include information on whether or not these same individuals voted.

The chief electoral officer, in a letter to all three provincial party leaders, says the information is encrypted and there is no evidence it has been accessed.

The privacy breach is now under investigation by the Ontario Provincial Police and Ontario’s information and privacy commissioner.

Greg Essensa, the chief electoral officer, will hold a press conference at Queen’s Park on Tuesday morning.

His letter to the Ontario political leaders indicated that he takes the matter of the privacy breach "extremely seriously."