Progress on closing the gender pay gap is "dismally slow", according to equality charity the Fawcett Society.
At the current rate of decline it will take 60 years to eradicate the gap, the charity said.
New figures from the Office for National Statistics (ONS) indicate that in the year to April 2019, the gender pay gap for full-time workers rose to 8.9% - up from 8.6% the previous year.
But for people under 40, the gap for full-time employees was close to zero.
The gender pay gap is the percentage difference between average hourly earnings for men and women.
In 2012, the gap between what the average full-time female employee earned compared with the average man was 9.5%. This gap had only narrowed to 8.9% in 2019.
The pay gap for all workers fell from 17.8% in 2018 to 17.3% in 2019, and continues to decline, the ONS said.
The extent of the pay gap varies by age, with older female workers more likely to earn less in comparison.
Women over 40 are more likely to work in lower-paid occupations and, compared with younger women, are less likely to work as managers, directors or senior officials, the ONS said.
Sam Smethers, the Fawcett Society's chief executive, said: "Progress to close the gender pay gap is dismally slow and at this rate it will take 60 years to eradicate it.
"As we approach the 50th anniversary of the Equal Pay Act women have waited long enough.
"The pay gap represents a productivity gap and a waste of women's skills and potential. Too many women are trapped in low paid part-time work or locked out of non-traditional sectors while others experience pay or pregnancy discrimination."
Ms Smethers called for pay gap reporting by ethnicity, for medium-sized businesses to be included in reporting requirements, and for firms to be required to publish action plans.
She also said that the underlying causes needed to be addressed, "one of which is the unequal sharing of unpaid care work". Improvements would include better-paid periods of paternity leave for fathers, and making all jobs flexible unless there is a business case against.
TUC general secretary Frances O'Grady said it would take "decades" to close the gender pay gap at the current rate.
"Government must pick up the pace. It's clear that publishing gender pay gaps isn't enough on its own," she said.
"Companies must also be legally required to explain how they'll close them."
The British Chambers of Commerce (BCC) called for "more action to ensure women of all ages receive fair and equal pay at every level".
"Employers must identify and remove all barriers to training and career development opportunities to support women into senior level positions and enable parents and carers to thrive in skilled roles," said Jane Gratton, head of people policy at the BCC.
However, she added that "naming and shaming employers" through pay gap reporting was "a blunt and ineffective instrument".
"It does not help those who are trying and struggling to recruit women, and can deter women from applying," she said.
The gender pay figures were released by the ONS as part of a wider set about UK employee earnings.
The data showed that median weekly earnings for full-time employees increased by 2.9% to £585 from last year, but after inflation is taken into account, the increase was just 0.9%.
Moreover, median weekly earnings in real terms are still 2.9% lower than the peak of 2008, which they were £603 in 2019 prices.