According to figures produced by the Trades Union Congress (TUC), the number of people working for more than 48 hours per week has increased by 0.5 per cent this year to reach 3.3 million.
The congress cites current challenging market conditions as one of the factors behind the rise.
It goes on to suggest that this trend, in which important roles are increasingly reliant on long hours, may hamper efforts to close the gender pay gap, as female employees with childcare responsibilities are likely to be overlooked.
"Employees across the UK already work the longest hours in Western Europe and the recent increase will mean lower productivity, more stress and less time to have a life outside the office with friends and family," stated Midlands TUC regional secretary Roger McKenzie.
Recently, Sarah Veal, head of equality and employment rights at the TUC, described the gender pay gap as unjustified.
