The operator of Ivanka Trump's fashion brand has halted negotiations with major Japanese apparel company Sanei-International Co. over concerns about potential conflicts of interest, according to a letter from the operating company.

Trump serves as an adviser to her father, U.S. President Donald Trump, and potential conflicts of interest between the Trump family's businesses and public duties have been an issue of concern since he took office.

According to the letter from an executive of Ivanka Trump Operations LLC, dated May 17 and addressed to a ranking member of the U.S. House of Representatives Committee on the Judiciary, the company and Sanei agreed in principle on a potential transaction in August 2016. The letter was made public on Monday.

However, the company notified Sanei in January that it "decided not to pursue further negotiations" as it has learned Sanei-International's parent company had ties to the Japanese government.

Ivanka Trump resigned from her positions at the business in January and subsequently placed it in a trust out of concerns over possible conflict of interest with respect to the business's potential expansion into foreign markets, according to the letter.

Information disclosed by Sanei's parent company TSI Holdings Co. showed TSI's largest shareholder was the state-owned Development Bank of Japan as of the end of February.

The New York Times reported Monday that lawmakers say they "remain concerned" about Ivanka Trump possibly using the White House to further her private interests.