Women often do lower paid work
The new measures are designed to close the gender pay gap in the UK and are due to be announced by the Trade and Industry Secretary, Patricia Hewitt, on Wednesday.
Companies could be taken to an employment tribunal if they refuse to comply with the employment law changes, which are in response to a report by the government's advisor on equal pay, Denise Kingsmill.
But it is anticipated the move will not go far enough to satisfy equal rights campaigners.
A pay questionnaire will be included in the Employment Bill currently going through parliament.
'Named and shamed'
Ms Kingsmill recommended that women should have the power to find out how much named male employees are paid.
The independent report on equal pay says that employers' attitudes to equal employment and pay should be open to public scrutiny.
It says companies should be forced to detail policies on these issues in their annual reports.
The government has agreed to look at how this could be implemented.
But it accepts the gap cannot be closed entirely because much of pay inequalities is due to motherhood.
Childcare failings
British women are paid on average 18% less than men for similar full-time jobs.
Women involved in part-time work are paid on average 39% less than their male counterparts.
Wednesday's announcement is likely to be welcomed by the Equal Opportunities Commission.
Its chair Julie Mellor had already suggested the government tighten up legislation aimed at reducing the wage gap.
But she went further by saying that much of the inequality was down to the national shortage of affordable childcare.