President Obama said in a statement Tuesday night that the IRS engaged in "intolerable and inexcusable" targeting of conservative political groups, pledging to hold accountable the civil servants responsible.

The president's statement came after the leak of a report by the Treasury Department's inspector general for tax administration that found IRS staffers used "inappropriate criteria" to target Tea Party groups, which were then placed under higher scrutiny.

"The federal government must conduct itself in a way that’s worthy of the public’s trust, and that’s especially true for the IRS," Obama said. "The IRS must apply the law in a fair and impartial way, and its employees must act with utmost integrity. This report shows that some of its employees failed that test."

Earlier this week, Obama said that, if confirmed by the inspector general's report, reports the agency had targeted conservative groups were "outrageous."  With the release of the report, the president vowed accountability.

"I’ve directed [Treasury] Secretary [Jack] Lew to hold those responsible for these failures accountable, and to make sure that each of the Inspector General’s recommendations are implemented quickly, so that such conduct never happens again," Obama said.

Lew said in a statement Tuesday night that he was "deeply troubled" to learn about the report's findings.

"While the inspector general found no evidence that any individual or organization outside the IRS influenced the decision to use these criteria, these actions were inappropriate and did not reflect the high standards which I expect and the public deserves," he said.

"Like the American people, I have zero tolerance for any action that could undermine public confidence in the impartial and non-partisan administration of the tax code."

He said despite IRS efforts to stop the targeting as of May 2102, "it should never have happened and must not happen again" and he expects the recommendations to be implemented "without delay."

At a press briefing earlier Tuesday, White House press secretary Jay Carney refused to say whether that accountability would include the firing of low-level employees or acting IRS Commissioner Steven Miller. Sen. Marco RubioMarco Antonio RubioColbert: Students taking action on gun violence 'give me hope' Lawmakers feel pressure on guns Florida lawmaker's aide fired after claiming shooting survivors were 'actors' MORE (R-Fla.) has already called for Miller's ouster, although Douglas Shulman served as the agency's commissioner during the time when conservative groups were first targeted. Lawmakers have criticized Miller for not telling them about the targeting for more than a year.

The agency, the report found, asked for a range of “unnecessary information” from groups seeking tax-exempt status – including donors, all of the issues important to that organization and the political affiliations and aspirations of group leaders.

The inspector general's report also found that the IRS, while taking steps to end political targeting, “will need to do more” to reassure the public. It accuses IRS leadership of "insufficient oversight" and employees of "inconsistent treatment of organizations applying for tax-exempt status."

Obama said Tuesday that "regardless of how this conduct was allowed to take place," the actions were improper. Earlier in the day, Carney categorically denied that anyone on the president's political staff might have influenced the IRS to target conservative groups.

"The bottom line is, it was wrong," Obama said. "Public service is a solemn privilege. I expect everyone who serves in the federal government to hold themselves to the highest ethical and moral standards. So do the American people."

Miller and Russell George, the tax administration inspector general, are scheduled to discuss the findings at a House Ways and Means hearing on Friday.

--Vicki Needham contributed.

--This report was originally published at 8:53 p.m. and last updated at 10:18 p.m.