Story highlights The Hatch Act prohibits most employees in the executive branch from engaging in political activity

Senior White House aide Dan Scavino was reprimanded in April by the OSC for violating the act

Washington (CNN) US Ambassador to the United Nations Nikki Haley was warned on Tuesday that her retweet of a political message posted by President Donald Trump in June endorsing then-South Carolina congressional candidate Ralph Norman was a violation of the Hatch Act, according a letter posted by a Washington watchdog group.

"The Office of Special Counsel issued Haley a warning letter noting that any future engagement in prohibited political activity will be considered 'a willful and knowing violation of the law, which could result in further action,'" according to a press release from the Citizens for Responsibility and Ethics (CREW), which filed the original complaint.

The Hatch Act prohibits employees in the executive branch, except the President, vice president and some other high-level officials, from engaging in political activity.

A spokesperson for the OSC told CNN that they do not comment on the status of such investigations.

Haley did not immediately respond to CNN's request for comment.

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