Conducting an employment audit is the first step in improving company performance through the better management of people

Denise Kingsmill, Competition Commission

On average, for every �1.00 a man earns, a woman gets only 82p across both the public and private sectors.

Ms Kingsmill said: "Conducting an employment audit is the first step in improving company performance through the better management of people.

"The encouraging support of these companies illustrates the importance of good management of human capital."

So far, Ms Kingsmill has visited more than 50 groups as part of the consultation phase of the review and she is due to report back to the government this autumn.

Closing the gap

Minister for Women Sally Morgan said: "We are committed to closing the pay gap and are working with business to achieve it.

"The introduction of the minimum wage gave over one million women an instant pay rise.

"But there is clearly still much to be done to close the 18% gap.

"That's why we asked Denise Kingsmill to carry out a review.

Women are still being paid less than men

"Denise has clearly been making good progress talking to companies and today's announcement that nine blue-chip companies are taking steps to ensure pay equality by conducting voluntary pay audits is very welcome."

The other companies which have agreed to carry out a review are Citigroup, Unilever, Littlewoods, Compass and Centrica.

As well as looking at differences in salary, the nine companies will examine issues like whether women are put into certain types of job, such as administrative posts and support roles, which may limit their ability to get promoted.

They will also look at the rate at which men and women get promoted.