The Treasury Department's watchdog agency for the Internal Revenue Service said it has found around 6,400 emails to and from Lois Lerner, the former head of the Internal Revenue Service's nonprofit division, that have not previously been given to Congress, CNN reports.
Ms. Lerner has been at the center of an inquiry into the IRS's scrutiny of conservative groups applying for nonprofit tax status.
About 650 of the emails are from 2010-11 when the alleged targeting of Tea Party groups began.
Last year, the agency said it had found as many as 30,000 emails to and from Ms. Lerner. The Senate Finance Committee asked the IRS inspector general to investigate whether thousands of additional emails that had allegedly been lost due to a hard-drive crash could be recovered.
Earlier this month the Justice Department said it would not pursue criminal contempt charges against Ms. Lerner for refusing to answer congressional questions about the agency's practices. Last year Ms. Lerner refused to testify before Congress for a second time.