One of Silicon Valley's top black female executives, Bozoma Saint John, has left tech giant Apple to join ride-hailing service Uber.

Ms Saint John, who was born in Ghana before moving to the US when she was a teenager, was a marketing executive at Apple and has now taken on the role of Uber’s new Chief Brand Officer, the company announced on Twitter:

Her appointment comes at a time when Uber has been criticised for its management practices and company culture, TechCrunch reports

The company has just fired 20 workers after an investigation on sexual harassment.

Ms Saint John was widely praised for her presentation last year at Apple's annual Apple Worldwide Developers Conference, where the company shows off its latest innovations.

During her presentation about new features on Apple Music app she played Ghanaian High Life hit Ye Wo Krom.