Senior officials at the US tax agency knew agents were targeting conservative political groups as early as 2011, according to a draft of an inspector general's report obtained by The Associated Press that seemingly contradicts public statements by the commissioner of the Internal Revenue Service.

The IRS apologized Friday for what it acknowledged was "inappropriate" targeting of conservative political groups during the 2012 election to see if they were violating their tax-exempt status. The agency blamed low-level employees, saying no high-level officials were aware.

But on June 29, 2011, Lois G Lerner, who heads the IRS division that oversees tax-exempt organizations, learned at a meeting that groups were being targeted, according to the watchdog's report. At the meeting, she was told that groups with "tea party," ''patriot" or "9/12 project" in their names were being flagged for additional and often burdensome scrutiny, the report says.

Lerner instructed agents to change the criteria for flagging groups "immediately", the report says.

"Tea party" and "patriot" are favorite terms of the small-government conservative movement that has emerged in recent years and is highly critical of President Barack Obama. The 9-12 Project is a group started by conservative TV personality Glenn Beck.

The revelation that the IRS targeted those groups is becoming a new headache for the Obama administration, which is already confronting a highly polarized, partisan atmosphere in Washington.

On Saturday, White House spokesman Jay Carney said in a statement that Obama is concerned that "a small number" of IRS employees may have fallen short of the high level of integrity expected of public servants.

"We understand that the matter is currently under review by the inspector general," Carney said. "If the inspector general finds that there were any rules broken or that conduct of government officials did not meet the standards required of them, the president expects that swift and appropriate steps will be taken to address any misconduct."

The Treasury Department's inspector general for tax administration is expected to release the results of a nearly yearlong investigation in the coming week. The AP obtained part of the draft report, which has been shared with congressional aides.

Among the other revelations, on August 4, 2011, staffers in the IRS' Rulings and Agreements office "held a meeting with chief counsel so that everyone would have the latest information on the issue."

On January 25, 2012, the criteria for flagging suspect groups was changed to, "political action type organizations involved in limiting/expanding Government, educating on the Constitution and Bill of Rights, social economic reform/movement," the report says.

While this was happening, several committees in Congress were writing IRS Commissioner Douglas Shulman to express concern because tea party groups were complaining of IRS harassment.

In Shulman's responses, he did not acknowledge targeting of tea party groups. At a congressional hearing March 22, 2012, Shulman was adamant in his denials.

The portion of the draft report reviewed by the AP does not say whether Shulman or anyone else in the Obama administration outside the IRS was informed of the targeting. It is standard procedure for agency heads to consult with staff before responding to congressional inquiries, but it is unclear how much information Shulman sought.

The IRS has not said when Shulman found out that tea party groups were targeted.

Shulman was appointed by President George W Bush, a Republican. His six-year term ended in November. Obama has yet to nominate a successor. The agency is now run by an acting commissioner.

The IRS said in a statement Saturday that the agency believes the timeline in the IG's report is correct, and supports what officials said Friday.

"IRS senior leadership was not aware of this level of specific details at the time of the March 2012 hearing," the statement said. "The timeline does not contradict the commissioner's testimony. While exempt organizations officials knew of the situation earlier, the timeline reflects that IRS senior leadership did not have this level of detail."

Lerner's position is three levels below the commissioner.

Several congressional committees have promised investigations, including the Ways and Means Committee, which plans to hold a hearing.

The group Tea Party Patriots said the revelation was proof that the IRS had lied to Congress and the public when Schulman said there had been no targeting of Tea party groups.

"We must know how many more lies they have been telling and how high up the chain the cover-up goes," Jenny Beth Martin, the group's national coordinator, said in a statement Saturday.

"It appears the IRS committed crimes and violated our ability to exercise our First Amendment right to free speech. A simple apology is not sufficient reparation for violating the constitutional rights of United States citizens. Therefore, Tea Party Patriots rejects the apology from the Internal Revenue Service," Martin said.

On Friday, White House spokesman Jay Carney said the administration expected the inspector general to conduct a thorough investigation, but he brushed aside calls for the White House itself to investigate.