Female employees earn up to 43.5% less at Barclays than men, according to gender pay gap figures it has submitted to the government.
Only 28 of the 1,154 companies that have reported the figures have a higher median hourly pay gap than Barclays.
Barclays chief executive Jes Staley said it had “more work to do” so women could progress in financial services.
However, Barclays said that it paid men and women in the same roles equally.
The 43.5% average gender pay gap reflects its investment bank division, Barclays International. For its UK retail bank, women earn 14.2% less than men on average, while the figure is 29.9% for the holding company, Barclays Services.
The bank has not produced an overall figure for the three divisions.
Nicky Morgan, chair of the Treasury Select Committee, described the pay disparity at Barclays International as shocking, adding: “Financial firms should be prepared to explain any gender pay gap that they may have.”
Mr Staley said: “Although female representation is growing at Barclays, we still have high proportions of women in more junior, lower paid roles and high proportions of men in senior, highly paid roles.
“There has been improvement across financial services but progress has been slow within the industry, so we support the objectives and intent of the UK government in introducing gender pay gap reporting to drive equality in both the workplace and in society more widely.”
Of all financial and insurance companies that have submitted their figures, the median pay gap is 14.8%.
The imbalance at Barclays UK was further highlighted by its pay quartile figures, with women accounting for 73% of the lowest-paid employees.
Women’s bonus pay at Barclays UK was 46.9% lower than that for men on the median measure.
Barclays is the first big bank to report its gender pay figures and chose to do so on the same day its annual results were released.
Women earn 38.4% less at Virgin Money, while insurer Aviva has a median pay gap of 27.6%.
Both firms, along with Barclays, have said they pay men and women in the same roles equally.
UK companies with 250 or more employees – about 9,000 firms – must calculate their gender pay gap and publish it on a government website by 4 April, or 30 March for the public sector.
Dominie Moss, founder of The Return Hub, which places women returning from career breaks in financial services jobs, said: “There’s no silver bullet – for banks and City firms it’s about getting more women established in senior executive roles, so they can in turn embed a culture that’s more attuned to the needs of both women and men. That’s going to be about changing managerial and recruitment practice.”