The BBC, Britain’s public broadcaster, is to be investigated over suspected discrimination following complaints that women have been paid less than men, the country’s equality watchdog announced on Tuesday.

The issue made headlines last year when senior broadcaster Carrie Gracie quit her job as BBC China editor in a highly public protest at being paid less than her male counterparts.

This followed an outcry in 2017, when the BBC published a list of its best-paid on-air staff, revealing two-thirds were men, some of whom were paid far more than their female peers.

The Equality and Human Rights Commission (EHRC), which is looking at records dating back to January 2016, said the BBC had provided a large amount of information on its pay policies.

“Having reviewed all of the information … we suspect that some women at the organization have not received equal pay for equal work,” the EHRC said in a statement.

The equality regulator, which acknowledged that the BBC had begun making reforms, will examine formal and informal pay grievances raised by staff and look at how they were resolved.

“Paying men and women the same salary for the same job has been a legal requirement for almost 50 years,” EHRC chief executive Rebecca Hilsenrath said in a statement.

The EHRC said it hoped to finish the investigation by the end of 2019.

Lawmaker Damian Collins, chairman of parliament’s media committee, welcomed the inquiry, saying it had been “a very distressing time for many BBC employees”.

BBC Director General Tony Hall said the organization had been through a “tremendous period of reform” and improvements had already been made.

“We try to be the gold standard of what everyone wants from society – openness, respect and equality,” he was quoted as saying on the BBC’s news site.

“We may not always succeed, but I am confident that we are a decent and fair employer.”

The BBC said in January 2018 it would implement “substantial” pay reductions for some men and pay increases for some men and women, following a report by auditors PricewaterhouseCoopers.

Britain enacted legislation outlawing sex discrimination in the 1970s and this was followed by an equality act in 2010.

But Sam Smethers, head of the Fawcett Society, a women’s rights charity which campaigns on equal pay, said pay discrimination was still common.

“We hope this results in lasting change at the BBC and acts as a warning to other employers too,” she said.