Washington (CNN) Treasury Secretary Steven Mnuchin failed to comply with federal ethics rules in the sale of his stake in a film production company to his wife, the federal government's ethics watchdog said.

After a more than eight-month delay in reviewing Mnuchin's 2018 financial disclosure form, the Office of Government Ethics declined to certify the secretary's filing for neglecting to disclose that ethics officials within the Treasury Department had advised him that his stake sold to his then-fiancee, Louise Linton, would not create a conflict of interest.

Mnuchin told the Senate Finance Committee at a hearing last month that department ethics officials had informed him he was allowed to sell his stake in StormChaser Productions to Linton. But the government's ethics office took issue with the matter for not being informed of the guidance by Treasury and not approving it.

Even so, ethics officials stopped short of imposing penalties on Mnuchin given his willingness to revise his federal ethics agreement and to recuse himself from government matters that could impact his wife's business.

"If while I am secretary the nature of StormChaser's business practices or the types of films it owns or produces changes, I will seek further guidance from the department's ethics official, who will consult with O.G.E.," Mnuchin wrote in a statement Thursday evening.

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