UN Women Goodwill Ambassador Emma Watson arrives for an activity to promote political shares at the Uruguayan Senate and Congress chambers at the Parliament building in Montevideo, September 17, 2014. [Photo/Agencies]

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Watson, who was appointed to the UN role in July, received a standing ovation as she called on men and women to reclaim feminism for the benefit of all.

She disclosed how she became a feminist after being told she was too "bossy" for wanting to direct a play aged eight.

"But my recent research has shown me that feminism has become an unpopular word," said Watson, who studied at Britain's Oxford University and Brown University in the United States.

"I was appointed six months ago and the more I have spoken about feminism the more I have realized that fighting for women's rights has too often become synonymous with man-hating. If there is one thing I know for certain, it is that this has to stop."

So far Watson has dedicated her humanitarian efforts as a Goodwill Ambassador to promote the empowerment of young women.

She has visited Bangladesh and Zambia to promote girls' education, and has recently returned from Uruguay.

Mlambo-Ngcuka said the engagement of young people was critical to advance gender equality in the 21st century.

"I am convinced that Emma's intellect and passion will enable UN Women's messages to reach the hearts and minds of young people globally," she said in a statement.