Firms were urged to examine their wage systems to make sure they comply with equal pay laws amid the continued gap between the earnings of men and women.

The Equality and Human Rights Commission (EHRC) said full-time female workers are paid 16.4% per hour less than men on average, rising to 21.6% in private firms.

The commission and the British Chambers of Commerce (BCC) published a new guide so employers can check pay systems in four hours.

BCC director general David Frost said: "Businesses want to pay people fairly for the job that they do. This guidance should help smaller businesses analyse any pay gap and make any changes required by law.

"Taking action now to make pay systems transparent and fair should help businesses recruit the best talent to enable the private sector to drive economic recovery."

Jean Irvine, an EHRC commissioner, said: "Employers need pay systems that are both transparent and fair. While transparency is not enough in itself to reduce the pay gap between men and women, it does provide clarity.

"It is difficult, if not impossible, to resolve a problem that cannot be seen.

"What we ask of small and medium-size employers is not difficult - it takes minimal time and effort but can offer a real return. Linking equal work to equal pay will see employees rewarded fairly for the work they do.

"Employees will enjoy the benefits of working for a company which actively promotes equality while employers will protect themselves from a potentially costly and time-consuming equal pay claim."

The EHRC guide follows a study which claimed it will be more than 50 years before the salaries of female managers are the same as their male counterparts.

The pay of female bosses rose by 2.8% in the last 12 months, but they earned £10,000 less on average than male managers.

At the current rate of progress, women managers will not be paid the same as men for 57 years, said the Chartered Management Institute (CMI).

The pay gap even existed at junior management level, with men being paid £1,000-plus more than women executives, according to a survey of more than 43,000 managers in 200 organisations.

The difference in pay was worse in companies in the Midlands, while the gap was smaller in the north east, said the report.

Around one in 12 female directors resigned last year, twice as many as men, possibly because of dissatisfaction with pay, said the CMI.