WASHINGTON (Reuters) - A former U.S. Internal Revenue Service official at the center of a controversy over the tax agency's treatment of Tea Party groups sent emails in which she appears to seek an audit involving a Republican senator, according to documents released on Wednesday by a House of Representatives committee.

The emails show former IRS official Lois Lerner received an invitation to an event in 2012 that was meant to go to Republican Senator Charles Grassley of Iowa. Grassley apparently received Lerner's invitation by mistake.

The event organizer apparently offered to pay for Grassley's wife to attend the event. Lerner, in an email to another IRS official, suggests referring the matter for an audit.

"Looked like they were inappropriately offering to pay for his wife. Perhaps we should refer to Exam?" Lerner wrote to colleague Matthew Giuliano.

Giuliano replied he was "not sure we should send an exam" and added that an audit would be premature because Grassley had not accepted the invitation.

The name of the event organizer was blacked out on copies of the emails released by the House Ways and Means Committee, and it was not clear if Lerner was suggesting Grassley or the group should be investigated.

Lerner's attorney, William Taylor, said in a statement: "She instructed her staff to return the letter and requested that the Exam section check to see if the organization's status permitted it to give the trip to Ms Grassley who was providing nothing in return."

Representative Dave Camp, the Republican chairman of the committee, expressed outrage over Lerner's actions.

"We have seen a lot of unbelievable things in this investigation, but the fact that Lois Lerner attempted to initiate an apparently baseless IRS examination against a sitting Republican United States senator is shocking," Camp said in a statement.

"At every turn, Lerner was using the IRS as a tool for political purposes in defiance of taxpayer rights," he said.

In May 2013, Lerner, who headed an IRS unit involved in applying extra scrutiny to conservative political groups' applications for tax-exempt status, apologized in public for what she called "inappropriate" review of the groups' applications. Republicans have been investigating since then.

She retired from the IRS in September 2013.

Last week, the IRS said a computer crash had caused it to lose some emails written by Lerner, angering Republican investigators who want the emails for review.

At a hearing of the House Oversight and Government Reform Committee this week, Republicans accused the IRS of hiding the Lerner emails and obstructing a congressional inquiry into the controversy.

(Reporting by Eric Beech; Editing by Mohammad Zargham)