Businesses employing more than 250 people must make figures showing average hourly rates paid to male and female employees publicly available under the new Equalities Bill.

From 2013 employers will have to publish details of average pay for men and women.

The Bill will also make it illegal for businesses to use ‘gagging clauses' that stop employees from disclosing information about their pay.

The Bill is expected to enter the statute books early next year and represents an ambitious attempt to reform about 100 items of equality legislation.

Public bodies must take action against discrimination on social background, and employers can select a candidate from an under-represented group if faced with choosing between two equally matched candidates, without risking a discrimination action. Positive discrimination which means less suitable candidates are offered jobs because they come from a minority group, will retain its current illegal status.

The Bill will also outlaw age discrimination when providing goods and services which means that travel insurance, for instance, must reflect the cost of risks rather than age categorisation.

Commenting on gender wage transparency, William O'Neill, of Rowlands, said: "The greater clarity and streamlining that the Equality Bill aims to deliver are welcome. Modern businesses in a competitive and increasingly global marketplace will benefit from broader diversity and transparency at senior levels, and unambiguous guidance on new positive action proposals will be of some assistance.”

William O'Neill added: "However, we are less enthusiastic about the proposal to make pay audits compulsory by 2013. Forcing businesses to publish their average female and male pay might appear reasonable, but the way to tackle the gender pay gap is not by comparing potentially misleading average pay rates, but by improving opportunities for women through better childcare and careers advice."