The gender pay gap has dropped slightly this year to a low of 17.9%, according to figures from the Office for National Statistics.

Women now earn 17.9% less than men, down from 18.4% last year. The rate for full-time workers has dropped from 9.1% to a low of 8.6%.

But the 0.5 percentage point drop was dismissed as “negligible” by the TUC, which said that at the current rate of progression it would take half a century for men and women to be paid the same.

“The government needs to crank up the pressure on employers,” said Frances O’Grady, TUC general secretary. “Companies shouldn’t just be made to publish their gender pay gaps, they should be legally required to explain how they’ll close them.”

Women aged 22-29 earn 1.3% less on average than men, but the gap widens after 30 and is more than 10% for those aged 40 plus.

“The gender pay gap has meant that women have historically been less able to save for retirement and have less scope to invest for their future, potentially storing up serious problems for later,” said Laura Suter, a personal finance analyst at AJ Bell.

The ONS figures show that average pay for a full-time worker in the UK has reached nearly £30,000 a year and is increasing faster than at any time since the 2008 financial crisis.

The Annual Survey of Hours and Earnings, considered the most authoritative measure of UK pay, found that the median gross weekly earnings for a full-time employee in 2018 was £569 a week, equal to £29,588 a year. That is a rise of 3.5% from £550 a week or £28,600 a year in 2017. But after taking inflation into account, average pay in real terms is still 3.7% lower than in 2008.

“Earnings are still only where they were in 2011, and have not yet returned to pre-downturn levels,” said Roger Smith, an ONS statistician.

Private sector pay increased faster than public sector earnings for the third year running . The wages of those in the private sector increased by 3.5% from 2017, compared with a 2.3% rise for those in the public sector.