Ride-sharing app Uber is looking for an additional $1b in funding.

The new round - the eight since the company was founded - will put Uber's valuation between $60 and $70bn, reports the New York Times.

Uber recently overtook smartphone company Xiaomi to become the world's most valuable privately-held business.

According to PrivCo, a data provider on privately-held companies, the money will be put towards battling competition with other ride-sharing and taxi-booking apps like Lyft and Hailo.

CEO Travis Kalanick says the company is still young, and so investors shopuld not be expecting it to go public.

"It's just a little early," he said, speaking at a Wall Street Journal press conference. "Give us some time ... something like that could happen but we're just not there yet."

Uber operates in over 300 cities in 68 countries, though the sailing has been far from smooth. It's ride-sharing service has been banned in Germany and Spain, and protests - sometimes violent - have been held in France, India and a number of other countries.