An appeals court ruled on Tuesday that a United Nations employee whose claims of sexual harassment led to the resignation of the UN refugee director cannot sue in United States courts.

The 2nd U.S. Circuit Court of Appeals upheld a lower court judge's decision to toss out the case brought by U.S. citizen Cynthia Brzak because the UN and its former employees are immune from such lawsuits, according to local media reports.

Brzak claimed that the UN high commissioner for refugees Ruud Lubbers had engaged in unwanted sexual conduct after a December 2003 meeting in his Geneva office.

Lubbers, the former Dutch prime minister, resigned from his position as the head of the UN refugee agency in February 2005 after a confidential UN report containing the allegations against him were leaked to the press.

The document also accused Lubbers of trying to influence the outcome of the investigation.

At the time, Lubbers denied the allegations and said he was resigning because of a lack of confidence in him.