Men are more likely to have been promoted to a senior management job in the past year, while no progress has been made on reducing the gender pay gap, says a new report.
Research showed the difference in promotion rates was one of the main causes of the gap in pay, which has widened from 22.8% last year, to 23.1%, said the Chartered Management Institute (CMI) and XpertHR.
A study of 60,000 employees found that 14% of men in management posts were promoted in the past year, compared with 10% of women.
The average salary for a male manager is almost £40,000, around £9,000 more than for women, said the report. Men also received higher bonuses.
Women fill 73% of junior management positions but only a third of company directors are female.
The report is published ahead of new regulations next year making it compulsory for large companies to publish pay rates for male and female employees.
Ann Francke, chief executive of the CMI, said: " Promoting men ahead of women is keeping us all back. Diversity delivers better financial results, better culture and better decision-making.
"Even before the new regulations kick in, employers need to get on board with reporting on their recruitment and promotion policies and how much they pay their men and women. Transparency and targets are what we need to deal with stubborn problems like the gender pay gap."
Mark Crail, of XpertHR, added: " The gender pay gap is not primarily about men and women being paid differently for doing the same job. It's much more about men being present in greater numbers than women the higher up the organisation you go.
"Our research shows that this gap begins to open up at relatively junior levels and widens, primarily because men are more likely to be promoted."