Female workers in their 30s are the worst affected by the gender pay gap, according to new research.

Figures produced by the Trades Union Congress (TUC) suggest that the difference between men and women’s full-time earnings increases from 3.3 per cent for women aged 22 to 29 to 11.2 per cent for females aged between 30 and 39.

The report, which is entitled Closing the Gender Pay Gap, cites a number of factors behind the differences in pay, including the undervaluing of women’s skills, so-called "employment penalties" for mothers and the concentration of women in low-paid jobs, such as childcare and cleaning.

"We all expect our wages to increase as our careers progress. But women’s wages start to stagnate as early as their 30s and many are paying an unacceptable penalty simply for having children," stated TUC general secretary Brendan Barber.

Last month, the TUC showcased a documentary highlighting a number of equal pay victories throughout the 20th century.