Records withheld by the U.S. Chemical Safety and Hazard Investigations Board have stalled an investigation by the Environmental Protection Agency’s internal watchdog group, according to a letter written by Inspector General Arthur A. Elkins Jr. on Sept. 5 and released Tuesday.

The IG sent what is known as a “seven day letter" following CSB’s Aug. 8 refusal to provide documents to the IG in part of a law enforcement investigation. The documents requested were emails between “high level CSB officials” and outside legal counsel.

A seven day letter is written when “the IG becomes aware of particularly serious or flagrant problems, abuses, or deficiencies relating to the administration” of federal agencies, as required by the Inspector General Act of 1978.

On Aug. 27, the CSB confirmed that it had the requested documents, but told the IG that releasing them would waive its attorney-client privilege.

“The IG Act is unambiguous that IGs have access to all agency records without qualification,” Elkins said in his letter. “It is an implausible interpretation of the IG Act that Congress intended for agencies to be able to withhold information from IGs based upon a claim of privilege."

CSB Chairman Rafael Moure-Eraso was required by law to forward the document to appropriate congressional committees, such as the House Committee on Oversight and Government Reform, by Sept. 12.

The committees were notified, but there is no estimated date of resolution, according to the IG. The full letter is available here.