HSBC has worst gender pay gap among Britain's largest companies

* HSBC says men paid 59 percent more than women on average

* Companies have until Wednesday to submit gender payfigures

By Andrew MacAskill and William James

LONDON, April 4 (Reuters) - HSBC, Europe's largestbank, has reported the largest difference in male and femalestaff salaries among large organisations in Britain, as thegovernment looks to pressure big companies to reduce gender paydisparities.

Swamped by the task of delivering Brexit, Prime MinisterTheresa May is under pressure to make visible progress on adomestic agenda set out when she took power in July 2016,particularly after a snap election in 2017 that exposed aweakness on social reforms.

Hoping to highlight gender discrimination and forcecompanies into action, May has implemented long-planned reformsordering companies with 250 or more employees to publish detailsof the salary difference between male and female employees byWednesday evening and report back annually on the pay gap.

HSBC on average paid men 59 percent more than women, thebiggest difference among companies with more than 5,000employees in Britain, according a Reuters analysis of thepublished data using the mean as the measure.

The next largest gender pay gaps were at Virgin Atlantic,where men received 58 percent more on average more than women,followed by a unit of Barclays, where female staffearned 48 percent less than male colleagues.

HSBC said it was confident in its approach to pay and madeappropriate adjustments if it identified differences between menand women in similar roles which could not be explained byperformance or experience.

Virgin Atlantic said the gap reflected the relatively lownumber of female pilots in the aviation industry, while Barclayssaid it had more work to do so women could progress in theircareers at the company.

Firms are not required to break down the data in detail,leading to criticism that the average figures could obscure orexaggerate demographic explanations for disparities.Nevertheless, they offer a step forward in assessing the issue.

EQUALITY POLICIES

Almost 50 years since the passage of Britain's equal payact, the continued gulf in earnings between men and women hassteadily risen up the political agenda. The opposition LabourParty first created powers on gender pay reporting in 2010, butthen lost an election. May enacted those powers last year.

Although part of a broader trend of pro-equality policies inBritain, the issue has gained momentum under May, the country'ssecond ever female leader, and increasing competition from hermain opponent, socialist campaigner Jeremy Corbyn.

May vowed in 2016 to tackle "burning injustices" in society,with a specific reference to gender pay alongside issues likerace and class discrimination.

Nearly two years later, she said that by introducing thereporting requirement, her government had taken a lead on theissue.

"By making this information public, organisations will nolonger have anywhere to hide," she wrote in the Daily Telegraphnewspaper. "Shareholders and customers will expect to seeimprovements, and will be able to hold organisations to accountif they fail to achieve them."

Other countries to introduce mandatory gender pay gapreporting include Australia, which passed similar legislation in2012, and Germany.

Reuters analysed pay figures for 491 of the leadingcompanies, government departments, charities, local authoritiesand hospital trusts, which employ more than 5,000 people.

Of those organisations that had published data by 3 p.m.(1400 GMT) on Wednesday, 97 percent pay men more than women andjust 3 percent pay women the most.

The average gender pay gap among these largest companies is15.5 percent, according to the Reuters analysis.

Political opponents, including Labour, welcomed publicationof the data as a step forward but urged a more hands-onapproach, saying the government still lacked clear plans on howto address the problems they had revealed.

"(Theresa May) wants to close the #paygap but says nowherehow she plans to do it. Politicians can't just keep beating upbusiness while leaving structural inequality untouched," tweetedSophie Walker, leader of the Women's Equality Party.(Editing by Guy Faulconbridge and David Holmes)