"I have not violated any IRS rules or regulations, and I have not provided false information to this or any congressional committee," she said. "Because I am asserting my right not to testify, I know that some people will assume that I have done something wrong. I have not."

That Lerner chose to give an opening statement before asserting her Fifth Amendment right against self-incrimination angered some lawmakers.

Republican U.S. Representative Trey Gowdy from South Carolina said Lerner had effectively waived her Fifth Amendment right and demanded that she stay to answer questions.

House Oversight Chairman Darrell Issa, a California Republican, also said Lerner appeared to have waived her right, but dismissed her from the hearing as photographers surrounded her as she left.

Lerner is at the center of a scandal over the tax-collection agency's use of search terms like "Tea Party" and "patriots," to select groups for additional scrutiny.

The political firestorm over the scandal has undercut President Barack Obama's second-term agenda as the president tries to negotiate a budget deal with Republicans and push a comprehensive immigration reform bill through Congress.

Lerner made the IRS targeting public on May 10, sparking investigations by three congressional committees and the Department of Justice.

Congressional investigators have said Lerner was the Washington official who learned in June 2011 that workers in a Cincinnati, Ohio, office were using inappropriate criteria and ordered them changed.

Issa has accused Lerner of providing "false or misleading" information to Congress last year about the IRS' treatment of conservative groups seeking tax-exempt status.

Before Lerner's appearance, Issa said an IRS internal review uncovered the policy of scrutinizing conservative groups in May 2012 and top officials, including outgoing acting IRS Commissioner Steven Miller, were made aware of the findings but did not alert Congress for nearly a year.

He also questioned why an inspector general looking into the targeting allowed an IRS official to be present during investigative interviews with subordinates, and criticized the inspector general for waiting 10 months to give the committee information on the targeting.

"That in fact is perhaps the greatest failing of an otherwise well-regarded inspector," he said.

Issa said the employees in the IRS tax-exempt unit "—could have and should have been a whistleblower" on the targeting.

— By Reuters