By Kieran Guilbert

LONDON, April 5 (Thomson Reuters Foundation) - About 1,500 large British companies that failed to meet a government deadline to report the pay gap between male and female employees could face legal action, Britain's equality watchdog said on Thursday.

A law introduced last year requires companies and charities with more than 250 workers - covering almost half of Britain's workforce - to report their gender pay gap each year by April 4.

More than 10,000 employers met the midnight deadline, with data showing that almost eight in 10 pay men more than women on average, while only 14 percent pay female staff higher salaries.

Britain's Equality and Human Rights Commission (EHRC) said the 1,500-odd companies that had not met the deadline would be given a month to comply before the watchdog took action - which could lead to court proceedings and result in unlimited fines.

"Reporting gender pay gaps is not optional; it is a legal requirement, as well as being the right thing to do," Rebecca Hilsenrath, chief executive of the EHRC, said in a statement.

"We will soon be starting enforcement against all employers that haven't published," she added.

As in many other countries, gender pay inequality has been a persistent problem in Britain despite sex discrimination being outlawed in the 1970s, and has sparked a public debate in recent years over why wages are still so different for men and women.

The overall gender pay gap in Britain stands at 18.4 percent, according to government data published last year.

HSBC, Virgin Atlantic and a unit of Barclays were among the largest companies with the biggest gender pay gap - at 59, 58 and 49 percent respectively - according to a Reuters analysis of the published data using the mean as the measure.

Companies are not required to break down the data in detail, leading to criticism that the average figures could obscure or exaggerate demographic explanations for disparities. Yet they mark a turning point for women in the workplace, advocates say.

"By finding out what their colleagues earn, women are then in a position to challenge any pay inequality," Sam Smethers, chief executive of the Fawcett Society, a UK-based women's rights group, told the Thomson Reuters Foundation by email.

"We are calling on women everywhere today to take that first step and simply have the conversation about pay," she added.

(Reporting By Kieran Guilbert, Editing by Megan Rowling. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, property rights, climate change and resilience. Visit http://news.trust.org)

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