The FBI says it's begun an investigation into the theft of personal tax information of more than 100,000 taxpayers from an Internal Revenue Service website.
The FBI said Thursday that agents were "working to determine the nature and scope of this matter." The agency is advising individuals it's contacted to take steps to safeguard their personal information.
IRS Commissioner John Koskinen has said the information was stolen as part of an elaborate scheme to claim fraudulent tax refunds.
Two officials told The Associated Press on Wednesday that IRS investigators belief the identity thieves are part of a sophisticated criminal operation based in Russia.
The information was taken from an IRS website called "Get Transcript," where taxpayers can get tax returns and other tax filings from previous years.