CEO Travis Kalanick said he will let his leadership team run the troubled ride-hailing company while he's gone. "It's hard to put a timeline on this - it may be shorter or longer than we might expect," the 40-year-old Kalanick wrote in a memo to employees on Tuesday.

He said he needs time off to grieve for his mother, who died in May. He also said he's responsible for the company's current situation and needs to become a better leader.

"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."

Investigation into misconduct and sexism

Uber simultaneously released a 13-page document calling for major reforms at the company based on a probe led by former US attorney general Eric Holder, who investigated allegations of misconduct and sexism.

The report, recommendations of which were adopted by the board, said Uber "should reformulate its written cultural values because it is vital that they reflect more inclusive and positive behaviors."

Uber released all of Holder's recommendations, but not the full report in order to protect the privacy of those filing complaints.

Holder's firm, Covington & Burling LLP, and a second firm, Perkins Coie, were asked to conduct separate examinations of Uber's workplace culture after a former engineer leveled charges of sexual harassment.

More than 200 complaints scrutinized

Susan Fowler posted a blog in February that detailed sexual harassment during the year she spent at Uber. Fowler wrote she was propositioned by her manager on her first day with an engineering team. She reported him to human resources, but was told he would get a lecture but no further punishment because he was a "high performer," she wrote.

Holder's investigators conducted more than 200 interviews with current and former employees, including people who had knowledge of Fowler's allegations, according to the law firm's recommendations.

After Fowler's blog, Uber made changes in human resources and opened a 24-hour hotline for employees.

Last week, the company fired 20 people including some managers at the recommendation of Perkins Coie, which probed specific complaints made to the company about sexual harassment, bullying, and retaliation for reporting problems. That firm checked into 215 complaints, with 57 still under investigation.

Cutthroat practices

Liane Hornsey, Uber's chief human resources officer, said implementing the recommendations "will improve our culture, promote fairness and accountability, and establish processes and systems to ensure the mistakes of the past will not be repeated."

The report also recommends that Uber make sure its workforce becomes more diverse from the top down. Uber's diversity figures are similar to the rest of Silicon Valley, with low numbers for women and underrepresented minorities. In the U.S., less than a third of the company's workers are female.

The Holder investigation was also charged with looking into cutthroat practices to thwart rivals and evade regulators. Uber faces questions about its covert use of a software to trick regulators and tactics apparently aimed at disrupting rivals in the ride-sharing business.

Under Kalanick, Uber has disrupted the taxi industry in hundreds of cities and turned the San Francisco-based company into the world's most valuable startup. While the company has not gone public yet, its valuation has climbed to nearly $70 billion.

Kalanick lost his temper earlier this year in an argument with an Uber driver who was complaining about pay, and Kalanick's profanity-laced comments were caught in a video that went viral.

In Europe, Uber has faced legal troubles in several countries, and some of its services have been banned.

bea/msh (AP, AFP, dpa)