Actress Emma Watson (L) and United Nations Secretary General Ban Ki-moon are shown the way to the exit following a photo opportunity promoting the HeForShe campaign in New York September 20, 2014. [Photo/Agencies]

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Watson, 24, who rose to fame as Hermione in the Harry Potter movies, gave her first major speech as a United Nations Women's Goodwill Ambassador in New York on Saturday, launching the "HeForShe" campaign to unite men and women for gender equality.

The initiative urges men to join the fight against violence and discrimination of women and by 1600 GMT (12:00 p.m EDT) on Tuesday, more than 70,000 men and boys had signed online pledges, according to the HeForShe online active map on the campaign's website.

The target is to mobilize one billion men and boys over 12 months with an online map showing exactly where men sign up.

"I hope we can all finally change laws and mentalities in order to establish what is nothing more than common sense," Watson posted on her Twitter account on Tuesday.

As the campaign gained momentum, men from all walks of life pledged to "take action against all forms of violence and discrimination faced by women and girls".

British actor Simon Pegg, known recently for playing Scotty in the Star Trek movies, tweeted: "Husband to a wife, father to a daughter, son to a mother. You bet I'm on board."

Organizers credited Watson's powerful speech for having such an impact and driving up numbers signing to the campaign.