Increasingly, as the issue takes center stage, companies are being pressed to publish their own reports on how much they pay each sex. U.K. businesses that have more than 250 employees are required legally to make their gender pay gap data available to the public by April.
One of the latest to disclose its figures was the Royal Bank of Scotland (RBS), whose chief financial officer made clear Thursday that more needs to be done to combat gender pay disparity.
"I think what it reflects is a lack of progress on senior women [into] positions in the bank, so about 37 percent of our top managers in the bank are female. We need to improve that," CFO Ewen Stevenson told CNBC in an interview.
When it released its annual report in February, RBS revealed that it paid women on average 37 percent less than men, with the company saying the pay gap reflected an under-representation of women at senior levels, which was "not a satisfactory position" in its view.
"We have a positive action approach in place, tailored by business, according to the specific challenges they face. As we continue to increase the proportion of women working in senior roles, we expect our gender pay gap will lessen," the lender's report said.
In terms of set targets, RBS has stated that by 2020 it wants at least 30 percent of people in its top three "leadership layers across each franchise and function" to be senior women. The bank's chairman, Howard Davies, said in the report that 44 percent of RBS' top 5,000 roles were taken by women, yet the group was hoping to achieve full gender balance at all levels by 2030.
Stevenson told CNBC that RBS was "very comfortable" paying two people equally if they both did the same job.
"We actually set ourselves a target a few years ago for 30 percent, so we're comfortably ahead of that, but as my teenage daughter constantly reminds me: until we're at 50, it's not job done," he said, adding that to really address the issue, RBS needed to get more women into senior roles.
Barclays, Wells Fargo, Citigroup and the Bank of England have all published their own gender pay statistics.
—CNBC's Joumanna Bercetche contributed to this report
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