Issa, R-Calif., chairman of the House Oversight and Government Reform Committee, said in a letter to acting IRS head Daniel Werfel the committee "will be forced to consider use of compulsory process" if "the IRS continues to hinder the committee's investigation in any manner," CNN reported Tuesday.
The letter did not specify the steps the committee would take but did mention impeding congressional investigators is a crime punishable by as much as five years in prison, CNN reported.
Issa accused the IRS of a systematic attempt to "delay, frustrate, impede, and obstruct the committee's investigation."
"Despite your promise to cooperate fully with congressional investigations, the actions of the IRS under your leadership have made clear to the committee that the agency has no intention of complying completely or promptly with the committee's oversight efforts," Issa said.
IRS spokeswoman Michelle Eldridge told CNN the agency is "aggressively responding to the numerous data requests we've received from Congress."
Issa said the IRS has turned over only 12,000 of 64 million pages of documents the committee demanded.
Eldridge said "the vast majority" of the pages demanded by Issa are unrelated to the committee's investigation into IRS handling of requests by politically oriented groups for tax-exempt status. She said 70 IRS attorneys -- out of 1,500 -- are working full time to comply with Issa's demands in a "time and labor intensive review process."
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