Updated

The House Ways and Means Committee this weekend released a timeline of interactions with the IRS and a list of 10 questions it will likely ask agency officials in an upcoming hearing -- following the agency acknowledging Friday that it targeted conservative political groups during the 2012 election season.

“The IRS absolutely must be non-partisan in its enforcement of our tax laws,” committee Chairman Dave Camp, R-Mich., said late Saturday. “The committee …will hold the IRS accountable for its actions.”

The tax-collecting agency on Friday acknowledged it flagged the groups for additional review to see whether they were violating their tax-exempt status.

On Saturday, a draft of an inspector general's report, to be released in full later this week, shows senior Internal Revenue Service officials knew agents were targeting Tea Party groups as early as 2011. That information seemingly contradicts public statements by IRS Commissioner Douglas Shulman.

The timeline shows that Louisiana Rep. Charles Boustany, chairman of the Ways and Means Subcommittee on Oversight, sent a letter to Shulman on Oct. 6, 2011, requesting information “regarding the tax-exempt sector.”

The timeline ends with a March 12, 2012, entry stating the IRS responded “with no mention of knowledge of targeting conservative groups.”

“Since the inception of this investigation, the Ways and Means Committee has persistently pushed the IRS to explain why it appeared to be unfairly targeting some political groups over others -- a charge they repeatedly denied,” Boustany said Saturday. “My greatest concern is what would have come from this blatant abuse of power if Ways and Means, as well as others, had not spoken up.”

Camp said within hours of the IRS acknowledgement Friday that his committee would hold a hearing on the issue.

Among the expected question, according to a committee document obtained by Fox News is: What steps, if any, has the IRS taken to ensure that the targeting of individuals and organizations does not occur in the future?

Another potential question is: When was the IRS commissioner made “aware of these unlawful practices, what steps were taken, if any, to halt the harassment of conservative organizations? Who was disciplined regarding these practices, if anyone?”