Ashton Kutcher is "proud" of Natalie Portman for voicing her frustrations about the gender pay gap in Hollywood

Ashton wrote on Twitter: "So proud of Natalie and all women who stand up for closing the gender pay gap!"

In her recent interview, Natalie confessed she should have been more annoyed than she actually was after learning of Ashton's fee.

However, Natalie conceded that her more modest salary still amounted to "a lot", and so she was less inclined to make an issue of it at the time.

She recently said: "Ashton Kutcher was paid three times as much as me on 'No Strings Attached'.

"I knew and I went along with it because there's this thing with 'quotes' in Hollywood."

She subsequently explained that the quotes represent a career-high payday for the film star.

Natalie continued: "His was three times higher than mine so they said he should get three times more.

"I wasn't as p***ed as I should have been. I mean, we get paid a lot, so it's hard to complain, but the disparity is crazy."

What's more, Natalie - who is currently pregnant with her second child with husband Benjamin Millepied - said the pay gap is wider in the movie business than any other industry.

She said: "Compared to men in most professions, women make 80 cents to the dollar. In Hollywood, we are making 30 cents to the dollar."

Last year, fellow actress Jessica Chastain also bemoaned the pay gap in the movie industry and further afield.

The 39-year-old star claimed women are still valued on the basis of their attractiveness, rather than their competence.

She said: "People still think, 'Oh, why do women go on about the wage gap?' Well, it's across every industry.

"The only industries where women get paid more than men are industries where women's value lies in their body: prostitution, pornography, modelling.

"Those are the only industries where there's a wage gap the other way. Because the male gaze says, this is where you're valued. Your sex."