Washington (CNN) A top Environmental Protection Agency ethics official disclosed in a letter to the US Office of Government Ethics that he has referred "potential issues" related to agency chief Scott Pruitt to the EPA's internal watchdog for investigation.

In the June 27 letter, a copy of which was reviewed by CNN, Kevin Minoli, the EPA's principal deputy general counsel and designated agency ethics official, wrote that "potential issues regarding Mr. Pruitt have come to my attention through sources within EPA and media reports" and that he has "referred a number of those matters to EPA's Inspector General."

The New York Times first reported Saturday on the letter, which was sent to David Apol, the acting director and general counsel for the US Office of Government Ethics.

Pruitt's leadership at EPA has been the subject of intense scrutiny as he faces criticism and questions over his spending habits and ethical judgment. He is facing multiple inquiries into his actions as EPA administrator from ethics watchdogs, federal auditors and congressional committees.

An EPA spokesperson said in a statement to CNN that the letter "reports back to the OGE on a number of administrative and staffing issues, some of which predate the Trump Administration."

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