NEW YORK — A newspaper report yesterday said tens of thousands of eligible voters have been removed from rolls or blocked from registering in at least six swing states. Election officials lined up to defend their registration procedures and said they had done nothing wrong.

The New York Times based its findings on reviews of state records and Social Security data, and said it had identified apparent problems in Colorado, Indiana, Ohio, Michigan, Nevada and North Carolina.

The Times said voters appear to have been purged by mistake and not because of any intentional violations by election officials or coordinated efforts by any party. It says that some states are improperly using Social Security data to verify new voters' registration applications, and that others might have broken rules that govern removing voters from the rolls within 90 days of a federal election.

Elections officials in several states disputed that any voters were illegally removed from rolls. Michigan elections director Chris Thomas said the state removed only people who have died, notified authorities of a move or who were declared unfit to vote, which is well within the parameters of the law. Thomas said only 11,000 voters were removed from Michigan rolls in August — not 33,000, the figure cited in the report.

"There is no illegal purging going on," Thomas told The Associated Press yesterday.

The Times stood by its story. Spokeswoman Catherine Mathis said the newspaper's reporting was based on voter registration data provided by the states themselves, and in Michigan's case compared an Aug. 5 snapshot of registered voters with a Sept. 5 snapshot.

She said the Times explained its methodology to Thomas yesterday, "and he said he could not explain the discrepancy between our figures and Michigan's official numbers."

Colorado said it would review its practices of "canceling" voters who had moved, died or were deemed otherwise ineligible. Secretary of State Mike Coffman said he asked lawyers to determine if the state's protocols violated a federal ban on "systematic" purging close to an election, but said because people, not computers, were doing the reviews, he believed they were sound. He said nearly 2,500 voters may be restored if the procedure is found to have violated the law.

States have been trying to follow the Help America Vote Act of 2002 by removing the names of voters who should no longer be listed. But for every voter added to the rolls in the past two months in some states, election officials have removed two, the Times' review of the records found.

States appear to have violated federal law in one of two ways, according to the newspaper report. Some are removing voters from the rolls within 90 days of a federal election, which is not allowed except when voters die, notify the authorities that they have moved out of state or have been declared unfit to vote, The Times said.

And some of the states are improperly using Social Security data to verify registration applications for new voters, the newspaper reported.

Under the Help America Vote Act, many states have an agreement with the Social Security Administration requiring them to submit the last four digits of a new voter's Social Security number for verification if the person does not have a valid state-issued ID, such as a license.

Last week, amid concerns about an uptick in the number of requests for verification, Social Security Commissioner Michael Astrue sent a letter to officials in Alabama, Georgia, Indiana, Nevada, North Carolina and Ohio seeking to verify that the checks were run only on new voters who don't have acceptable identification. States have said the increase in checks is due partly to a stream of new voters coming in to register.

In Georgia, federal officials say some 2 million checks have been completed, but only 406,000 new voters were registered. The Department of Justice has questioned the checks, and state officials say they are trying to determine how federal authorities arrived at that figure.

North Carolina elections watchdog Bob Hall, who heads the advocacy group Democracy North Carolina, defended the state's elections board. Hall said he has found that many registration forms are incomplete or partly illegible and that many prospective voters provide Social Security numbers instead of driver's licenses. .

Indiana also defended its procedures.

"Using all available appropriate technology is our best way to combat voter fraud that we know exists in this state and across the country," Secretary of State Todd Rokita said in a statement yesterday.

Rokita spokesman Jim Gavin said no voters have been purged from Indiana rolls this year.

He said there has been a rise in the state's Social Security verification requests because a record number of Indianans — more than 4.4 million — are registered.

Nevada Secretary of State Ross Miller issued a statement calling the Times report misleading.

"I want to assure Nevadans that any suggestion that eligible voters will be denied their right to participate in this election on Nov. 4 is false," he said.