The investigator who wrote a scathing report about the Internal Revenue Service targeting tea party groups says he is “disturbed” the agency withheld newly released documents showing progressive groups may also have been singled out for additional scrutiny.

IRS Inspector General J. Russell George told a congressional panel Thursday the IRS did not provide the documents to his office during a yearlong audit. George said he just received the documents last week.

George issued a report in May that said IRS agents in a Cincinnati office improperly singled out groups with “tea party” and other conservative labels for additional scrutiny when they applied for tax-exempt status during the 2010 and 2012 elections.

George’s report blamed ineffective management for allowing the practice to continue for more than 18 months, delaying hundreds of applications for more than a year.

Since the revelations were made public, three congressional committees and the Justice Department launched investigations and much of the top leadership was replaced, including the acting commissioner.

“The reason the report focuses on the terms ‘tea party,’ ‘patriots’ and ‘9/12’ is that the IRS provided us a document at the beginning of our audit that shows these were the terms they used to select the potential political cases,” George told the House Oversight and Government Reform Committee.

Last month, the IRS provided documents to Congress that suggested some liberal and progressive groups may have been singled out for additional scrutiny as well — information that was not included in George’s May report. Some Democratic lawmakers said this was proof that George’s report was one-sided.

“The committee has obtained new documents that raise serious questions about the inspector general’s report, his testimony before Congress and his subsequent assertions in letters to members of Congress,” said Rep. Elijah Cummings of Maryland, the ranking Democrat on the oversight committee.

George, however, said he first saw the documents last week.

“They were not provided during our audit, even though similar documents that list ‘tea party’ but not ‘progressive’ were,” George said. “I am very disturbed that these documents were not provided to our auditors at the outset, and we are currently reviewing this issue.”

George also noted that IRS officials publicly agreed with his findings that the targeting focused on tea party groups.

“IRS staff at multiple levels concurred with our analysis citing ‘tea party,’ ‘patriot’ and ‘9/12′ and certain policy positions as the criteria the IRS used to select potential political cases,” George said.

The IRS did not respond to a request for comment.

The IRS was screening the groups’ applications because agents were trying to determine their level of political activity. IRS regulations say tax-exempt social welfare organizations may engage in some political activity, but the activity may not be their primary mission. It is up to the IRS to make that determination.

George’s report said applications from 298 groups were set aside for special scrutiny. Of those applications, 72 included the term “tea party,” 13 included “patriots” and 11 included “9/12,” the report said. No other labels were listed in the May report.

On Thursday, George said three groups had the word “progressive” in their name and four used the word “progress.”

(AP)