WASHINGTON — The Internal Revenue Service official who first disclosed that the agency had targeted conservative groups for special scrutiny, and in doing so ignited a controversy that has ensnared the White House, denied on Wednesday that she had ever provided false information to Congress. She then invoked her Fifth Amendment right against self-incrimination and declined to testify at a House hearing on the agency’s actions.

As the official, Lois Lerner, appeared under subpoena before the House Committee on Oversight and Government Reform, she sternly told her questioners that accusations that she had misled Congress in previous testimony were false.

“I have not done anything wrong. I have not broken any laws,” said Ms. Lerner, who leads the I.R.S.’s division on tax-exempt organizations. “I have not violated any I.R.S. rules and regulations, and I have not provided false information to this or any other Congressional committee.”

Ms. Lerner has become a person of intense interest to Congressional investigators, who insist that she made, at best, incomplete statements when she said she first learned that her subordinates had singled out Tea Party groups after reading news media reports last year. An inspector general’s report found, however, that she was briefed on their actions as early as June 2011.