Twitter announces its chief operating officer has stepped down from the post

The microblogging company said Mr Rowghani will stay with the company as a strategic adviser to CEO Dick Costolo.

Mr Rowghani joined Twitter in 2010 as chief financial officer and became COO two years later. Before that, he served as CFO at Pixar Animation Studios.

Twitter said it will not name a replacement for Mr Rowghani and did not give a reason for his departure. His responsibilities will be shifted to other executives.

The San Francisco-based social media company has been trying to broaden its user base, most recently by luring in World Cup fans who want to follow teams and players using its service.

Meanwhile, Amazon is launching a music streaming service in the US for its Prime members, adding yet another freebie to its popular free-shipping plan.

Amazon will offer more than a million tracks for ad-free streaming and download to Kindle Fire tablets as well as to computers and the Amazon Music app for Apple and Android devices.

The service, called Prime Music, is likely to be integrated with an Amazon smartphone which is expected to be previewed soon.

People who pay $99 (£59) a year for Prime can listen to tens of thousands of albums from artists including Beyonce for no extra cost.

By adding music, Amazon is hoping to hook new customers and retain existing ones on its Prime free-shipping plan, which also allows subscribers to watch streams of movies and TV shows and gives Kindle owners a library of books they can borrow once a month.

Steve Boom, Amazon’s vice president of digital music, said the service will pay for itself and is not part of the reason why the company raised the price of Prime from $79 (£47) in March – a move Amazon said would cover higher shipping costs. Instead, the company will benefit because Prime members tend to buy more from Amazon and remain loyal customers.