Ridesharing service Uber has suffered another blow as the US city of Portland has sued the firm for not following the city's regulations.
Uber started services in Portland, Oregon, on 5 December without consent from local authorities, the city says.
"The city's lawsuit is asking for a declaration by the court that Uber is subject to the city's regulations," the city said in a statement.
"The lawsuit also asks the court to order Uber to stop operating in Portland until it is in compliance with the city's safety, health and consumer protection rules."
The city laws require all for-hire vehicles to be licensed, and it wants Uber to follow them. Until it complies with the laws, Portland wants Uber to shut down operations within city limits.
The city has issued a cease and desist, ordering Uber to halt operations there, and is asking the court to enforce the order.
"Our main concern is public health and safety, because the state invested in the cities the responsibility to do that," city mayor Charlie Hales said.
"Beyond that, though, is the issue of fairness. Taxi cab companies follow rules on public health and safety. So do hotels and restaurants and construction companies and scores of other service providers. Because everyone agrees: good regulations make for a safer community. Uber disagrees, so we're seeking a court injunction."
"Uber has received a tremendously warm welcome from riders and drivers in and around Portland. We appreciate the way residents have welcomed Uber into the Rose City, their support illustrates why it's time to modernise Portland transportation regulation," Reuters quoted an Uber spokeswoman as saying.
Uber had completed its latest funding round earlier, valuing it at $40bn (£25.6bn, €32.6bn) ahead of its planned initial public offering.
However, the US company has recently suffered a number of blows to its international expansion plan.
On 8 December, the company was banned from operating in the Indian capital New Delhi, after one of its drivers was arrested for raping a female passenger.
The 26-year-old woman, who used Uber's smartphone app to book a taxi on 5 December, was allegedly taken to a secluded area and raped.
The service was earlier banned in the Netherlands, as it lacked a special license that was required according to the laws of the country.