The BBC operates a “secretive and illegal pay culture” that systematically discriminates against women, according to one of its most senior journalists, who has quit her job as China editor after learning that two of her male peers were paid significantly more.

In a withering, open letter which she put online on Sunday night, Carrie Gracie — who spent part of last week as a guest anchor on Today, the BBC’s main morning news programme — accused her bosses of taking a “divide-and-rule” approach to female staff.

“We have felt trapped,” she wrote, in a letter first published by BuzzFeed News. “Speaking out carries the risk of disciplinary measures or even dismissal; litigation can destroy careers and be financially ruinous.” She accused the BBC of demanding non-disclosure agreements that were “unworthy of an organisation committed to truth”.