Washington (CNN) A White House staffer is leaving after he learned that he wouldn't receive a permanent security clearance after he admitted to smoking marijuana, Politico reported on Wednesday.

George David Banks, a National Economic Council staffer, told Politico that the White House counsel's office informed him that his application for a permanent clearance was being denied because he admitted to smoking marijuana in 2013. He offered his resignation shortly thereafter.

Banks, who worked as a special assistant to the president for international energy and environmental policy, is the latest White House official to resign over the past week. His departure comes amid increased scrutiny over staffers' background checks.

White House staff secretary Rob Porter resigned last Wednesday after his two ex-wives alleged that he was abusive during their marriages. Top aides at the White House were aware of the allegations last fall, and he was permitted an interim security clearance.

And David Sorensen, a speechwriter for the Council on Environmental Quality, resigned on Friday after The Washington Post reported on domestic abuse allegations against Sorensen. Sorensen's position did not require a security clearance, White House principal deputy press secretary Raj Shah said.

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