The gender pay gap is widening for some women and it will now take 100 years to close it, a campaign group has warned.
The Fawcett Society said younger women as well as older female employees were now seeing their pay fall behind that of men, claiming the drive to equalise pay is "going backwards".
The group dubbed Friday Equal Pay Day - the day in the year when women start to work for free because of the difference in the pay of men and women.
The date has not changed for three years, showing the lack of progress, said the society.
Chief executive Sam Smethers said: "The pay gap is widest for older women as it grows over our working lives but we are now seeing a widening of the pay gap for younger women too, which suggests we are going backwards, and that is extremely worrying.
"At a time when we are breaking the taboo of talking about sexual harassment in the workplace we need to wake up to the fact that a culture which tolerates or even fosters sexual harassment isn't going to pay women properly either, and we know that younger women are particularly likely to experience harassment."
Official figures show the gender pay gap based on median hourly earnings for full-time employees fell to 9.1%, from 9.4% in 2016, but for full and part-time workers the figure increased by 0.2% to 18.4%.
The gap is wider for women in their fifties, at 18.6%, but has significantly grown among women in their twenties - from 1.1% in 2011 to 5.5% this year, said the society.
More than half of female workers admit to feeling financially unprepared for their retirement, as evidence emerges of a gender savings gap, according to research by financial advice firm Close Brothers and the Pensions and Lifetime Savings Association.
The study found 51% of female workers feel financially unprepared, compared with about a third (35%) of male workers.
Young Women's Trust chief executive Dr Carole Easton said that, at the current rate, today's young women will be retired before equal pay becomes a reality.
She said: "The gap exists from the moment women start work. Young Women's Trust research shows that young women apprentices earn 8% less than their male counterparts, leaving them more than £1,000 a year worse off."
Anne Milton, minister of state for apprenticeships and skills and minister for women, said: "The pay gap won't close on its own - we all need to take action to make sure we address this.
"That is why we have introduced a legal requirement for all large employers to publish their gender pay and bonus data by April 2018.
"I'm pleased that some of our top companies are leading the way and have already reported. By shining a light on where there are gaps, they can take action to address it."
TUC general secretary Frances O'Grady said: "The Government needs to boost pay for undervalued jobs mainly done by women, such as social care, and ministers must do more to remove the barriers that stop women getting jobs in better-paid professions."
Rebecca Hilsenrath, chief executive of the Equality and Human Rights Commission, said: "We need to radically change our workplace culture by advertising jobs as flexible from day one and we must stop seeing women automatically as our primary caregivers.
"It is only by looking at big change and not just concentrating on numbers that we will close this gap, once and for all."