The 15% pay gap between men and women is likely to get wider, according to warnings from the Fawcett Society.
Speaking on national equal pay day, the Fawcett Society's chief executive Ceri Goddard said that reductions in the public sector could make the gap even wider.
"In recent years, progress on closing the gap has slowed, but as the age of austerity bites, we now face the very real prospect of the gap actually widening for the first time since records began," she said.
"The UK's workforce is experiencing dramatic change.
"With around three-quarters of a million public sector jobs predicted to go by 2017, government is pinning its hopes on the hundreds of thousands of women – who will make up the majority of those who will lose their jobs - being able to find work in the private sector."
National equal pay day marks the day in the year when women effectively start 'working for nothing' compared to men, as only 15% of the year's work days remain.
The Fawcett Society also claims that women's unemployment is at a 24-year high.
Their campaign comes just two weeks after a group of former Birmingham city council workers successfully sued their former employers for not entitling them to the same pay and bonuses as their male colleagues, potentially opening the door to many other similar claims.