Georgia's largest nonpartisan voting advocacy group requested Monday that Gov. Nathan Deal order an independent investigation into the massive data breach exposing 6 million voters' personal information.

In a hand-delivered letter, the League of Women Voters of Georgia called the breach “an obvious threat to the voter registration process.” It also said the state should be concerned that Georgians, “regardless of their political persuasion, will be deterred from registering to vote if they are not assured that their personal information will not be compromised and their personal finances put at risk”

The letter was signed by Elizabeth Poythress, the league's president. A spokeswoman for Deal declined to comment and, as has been standard since the breach became public Nov. 18, referred questions to the Georgia Secretary of State's Office.

Anyone registered to vote in Georgia was affected by the disclosure — some 6.2 million people.

Secretary of State Brian Kemp two weeks ago fired an IT employee over what he called a "clerical error." Kemp said the employee inadvertently added the personal data, including Social Security numbers and birth dates, to a public statewide voter file before it was sent out last month to 12 organizations who regularly subscribe to "voter lists" maintained by the state.

The groups receiving the data — delivered via compact discs — included state political parties, news media organizations and Georgia GunOwner Magazine.

Kemp, who says he became aware of the breach Nov. 13, has said all 12 data discs illegally disclosing the private information have either been recovered or destroyed, and that the data was not disseminated. He also denied the disclosure was a breach of the state’s voter registration system, saying the system itself was not hacked.