Uber boss Travis Kalanick takes time out from embattled firm
Travis Kalanick's decision comes as the firm is urged to address allegations of bullying and discrimination.
Uber's chief executive is to take a leave of absence as the taxi app firm grapples with accusations of harassment and discrimination.
Travis Kalanick, who recently admitted he needed to "fundamentally change and grow up", says he wants to think about "Uber 2.0" and "Travis 2.0".
He also needs time to grieve for his mother, who died in a boating accident last month.
Mr Kalanick told employees about his decision in an email as the firm was urged to transform its toxic culture.
"It's hard to put a timeline on this," the 40-year-old wrote about his break from the business. "It may be shorter or longer than we might expect."
Referring to his mother's death, he said: "I need to take some time off of the day-to-day to grieve."
He also requires space "to reflect, to work on myself, and to focus on building out a world-class leadership team".
"If we are going to work on Uber 2.0, I also need to work on Travis 2.0 to become the leader that this company needs and that you deserve," he added.
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As Mr Kalanick announced his absence, Uber released a 13-page document detailing major reforms at the firm.
On Sunday, the board voted unanimously to adopt all the recommendations made by a law firm hired to investigate deep-seated cultural problems, led by former US attorney general Eric Holder.
Mr Holder looked into allegations of ethical lapses and misconduct.
Uber "should reformulate its written cultural values because it is vital that they reflect more inclusive and positive behaviours", his report said.
It added that its values needed to be "more inclusive and contribute to a collaborative environment, including emphasising teamwork and mutual respect, and incorporating diversity and inclusiveness as a key cultural value, not just as an end in itself, but as a fundamental aspect of doing good business".
On Monday, senior vice president Emil Michael stepped down from the business.
Last week, Uber fired 20 employees after 215 harassment complaints were reviewed by another law firm in a separate investigation.
Under Mr Kalanick, the Uber app has revolutionised the taxi industry in hundreds of cities.
Now valued at close to $70bn (£55bn), it has fast become the world's most valuable start-up.
Mr Kalanick's leadership team will run the company while he is away.