MONTGOMERY – Alabama’s voting practices are again under scrutiny by the Justice Department, with state officials saying there was nothing improper about checking the Social Security numbers of more than 1 million voters.

Gov. Bob Riley and Secretary of State Beth Chapman, who have overseen Alabama’s voter registration system, say the system was not used to illegally remove anyone from the voter rolls.

The Justice Department was concerned that the number checked was far higher than normal. In a letter to the Justice Department on Friday, Chapman said that there has been a large number of voter registrations, and that a technical step in the verification process may have been a factor.

But she said an invalid Social Security or driver’s license number “does not and has not ever prevented a voter from registering in the State of Alabama.”

In some states, voters are automatically disqualified if the numbers don’t match. But Chapman and Riley’s spokesman said that in Alabama, discrepancies are reported to county voter registrars to review.

“We assume registrars went back and verified new and existing voters because it’s their job to make sure their lists are accurate,” said Riley spokeswoman Tara Hutchison.

The state’s voter rolls are maintained by a computer system that compiles registrations into a central database. It can verify a voter’s driver’s license number or the last four digits of the voter’s Social Security number.

A federal judge directed Riley’s Republican administration to develop the system after Alabama’s previous secretary of state, Democrat Nancy Worley, failed to meet a federal deadline to implement it in 2006. Riley turned the system over to Chapman, a Republican, on Sept. 23.

Under an agreement with the Social Security Administration, Alabama can verify the last four digits of Social Security numbers for people who do not have a state-issued ID, such as a driver’s license, that can be verified first.

Last week, the Justice Department and the Social Security Administration sent letters to Chapman, questioning why Alabama had checked the Social Security numbers of more than 1 million Alabama voter registrations between Oct. 1, 2007, and Oct. 1, 2008.

That equals one-third of the 2.9 million people on Alabama’s voter rolls.

Christopher Coates, chief of the Justice Department’s Voting Section, said Alabama’s volume of checks was “significantly higher” than normal for a state of Alabama’s size.

Neither Chapman nor Riley disputed that 1 million checks were performed.

In her letter to the Justice Department, Chapman said one reason was the large number of voter registrations in Alabama during the past year, in addition to people updating their voter registrations with new addresses or other information.

Adam Thompson, an election official in the secretary of state’s office, said voter registration forms have spaces for people to enter either their driver’s license number or Social Security number. If voters supply both and county voter registrars enter both into the computer system, the computer system checks both numbers.

Chapman is working to eliminate that double verification, he said.

The Justice Department has played a big role in Alabama’s election practices since the Voting Rights Act was enacted in 1965 to open Southern polling places to blacks. Because of Alabama’s past discrimination, any changes in state voting laws still have to be approved by the Justice Department.

The Justice Department had asked Chapman for explanations by Friday because of concerns about whether the state might be violating federal voting laws.

Neither the information supplied by the Justice Department nor by the governor or secretary of state broke down the Social Security verifications by race.

The verifications are not the only issue the Justice Department has with Alabama.

The department threatened this week to sue the state for not providing information about absentee voting by the military and residents living overseas during the 2004 and 2006 elections.