Citizens for Responsibility and Ethics in Washington (CREW) alerted OSC to the potential infraction after Haley retweeted a tweet by President Donald Trump advocating for the election of Republican Ralph Norman in the South Carolina special election to replace former representative and current Office of Management and Budget Director Mick Mulvaney.
CREW's complaint accused Haley, the former governor of South Carolina, of violating the Hatch Act, a 1939 law that restricts the political engagement of some executive branch employees. The organization released Tuesday a letter from OSC it received in response, noting that the office found Haley to be in violation and that she was issued a warning.
OSC noted that Haley's Twitter account uses her official government headshot as her profile picture, that the account's biography features her title as U.S. ambassador to the United Nations, and that the account links to the website for the U.S. mission to the United Nations.
"Because Ambassador Haley's personal Twitter account included so much indicia of her official role ... it gave the impression that she was acting in her official capacity when she used this account to retweet President Trump's message," reads the letter to CREW from OSC.
The office goes on to write that it decided a warning was sufficient given that Haley deleted the post after she became aware that she may have crossed a line and has not since engaged in further political activity.
The U.S. mission at the United Nations did not immediately provide a response when reached for comment.
In a press release, CREW notes that Haley is the third administration official to be reprimanded for ethics issues following a complaint of theirs.
In April, White House social media director Dan Scavino received a warning for violating the Hatch Act after using his personal account to tweet that he hoped Rep. Justin Amash, R-Mich., would lose his next primary race. In February, the White House said that counselor to the president Kellyanne Conway would receive ethics training after encouraging the public to buy Ivanka Trump-branded products during an interview from the White House briefing room.