Uber said losses narrowed in the first three months of 2017 to $708m (£549m) from $991m in the previous quarter.

The company does not report financial results publicly, but said it was "on a good trajectory towards profitability".

In recent months Uber has been shaken by scandals, high-profile sackings and allegations of sexism.

Mr Gupta, who has been head of strategic finance since 2015, will leave next month to join another start-up in San Francisco.

Uber chief executive and co-founder Travis Kalanick said: "Gautam is a world-class financial talent. Over the last four years, he has been indispensible in helping build Uber from an idea into the business it is today."

Uber is now looking for a chief financial officer who it is thought will help steer the company towards a flotation on the stock market in the next two years.

Growing fast

Uber is still growing fast, although it has never made a full-year profit.

In the first three months of the year, revenue rose 18% from the previous quarter to $3.4bn. In 2016, the company carried 700 million passengers in more than 70 countries, booked $20bn in rides and generated $6.8bn in net revenues.

However, it has also raised what is estimated to be more venture capital than any start-up in history, some $11bn, and it needs to prove to its private investors that it can turn a profit.

Meanwhile, the company has been haemorrhaging senior executives since the beginning of the year.

New York general manager, Josh Mohrer, and the head of Uber's self-driving unit, Anthony Levandowski, both left this week.

Mohrer is credited with building Uber in New York city from its early beginnings. He is leaving for a job at Tusk Ventures, which advises start-up businesses on regulatory issues.

Allegations

Mr Levandowski, who was considered critical in the development of Uber's self-drive projects, was fired for declining to testify in the lawsuit that Google owner Alphabet has brought against Uber.

The case involves the alleged theft of self-drive technology from an Alphabet subsidiary.

Other high-profile departures include vice-president of product Ed Baker; Uber president Jeff Jones; vice-president of engineering Amit Singhal; policy and communications chief Rachel Whetstone - a Briton; and the head of mapping, Brian McClendon.

Uber has also hired former US attorney-general Eric Holder and Tammy Albarran, both partners at the law firm Covington & Burling, to conduct a review of sexual harassment claims made by a former employee.

In March, Mr Kalanick was forced to apologise after a video emerged of him swearing at one of the company's drivers.

And at the end of last month, Mr Kalanick was struck by personal tragedy when his mother died in a boating accident near Fresno, California. His father, who was also on the boat, was seriously injured.