All-women shortlists for selecting parliamentary candidates will remain legal until 2030 under new plans to help create a "critical mass" of 200 female MPs.
The policy had been due to expire in 2015, but Harriet Harman, the minister for Women, said she was extending the law for 15 years to encourage more women to enter politics.
At present there are 121 women MPs, about one in five members of the Commons, but although the number has increased dramatically since 1996, estimates suggest it will take 60 years before they equal the number of men.
Ms Harman said: "The Government is committed to ensuring that our democracy is representative. We have fought for equal representation and that's why there are more women in Parliament than ever before, but we need more.
"The most effective policy for increasing women's representation has been making it lawful to have women-only shortlists. By 2030 we should have achieved a critical mass of 200 women MPs, which will act as a tipping point for a natural increase in the number of women in elected office. Women MPs have changed not only the face of Parliament, but the agenda of Parliament. I can remember when there was virtually no discussion in Parliament of maternity leave, domestic violence, or support for families caring for older relatives."