South Korean police have booked more than two dozen of Uber's Seoul-based employees and associates on suspicion of operating illegal taxi services.
Twenty-nine people, among them the head of Uber Korea, and also including the heads of six car rental firms, were "booked" on suspicion of connecting passengers to nearby cabbies without a licence, according to Yonhap News Agency.
This is far from the first sign of difficulty Uber has faced from Seoul, having previously suspended its service to seek clarity and compliance with local regulations.
Travis Kalanick, Uber's global CEO, was also indicted on suspicion of conducting an illegal business, adding to his existing indictment on charges of violating transportation laws while establishing Uber Korea.
"We plan to summon Kalanick soon and check the transaction details of overseas bank accounts to conduct further investigation into those involved in the case," a police official told Yonhap on condition of anonymity. "If Kalanick continues to disobey the summons, we plan to seek an arrest warrant against him."
Uber told The Register it has "fully cooperated with the police during the course of their investigation and we will continue to do so as the matter is referred to the prosecution for review".
"Uber does not believe the employees in Korea have engaged in any misconduct or illegal behaviour. We believe the prosecutors will come to a similar conclusion," it added.
Kalanick remains in the US and has yet to visit South Korea to sort things out.
Brent Callinicos announced his decision to step down as chief finance officer earlier this week, and it seems likely the company will be going public soon.