Police in southern China raided the office of U.S. car-hailing app Uber after the Chinese government in January banned drivers of private cars from offering such services through apps.

A statement by the Guangzhou Municipal Transport Commission said police suspected Uber was operating an illegal taxi service without a proper business registration. It said police seized thousands of iPhones and other equipment used to run the business in the Thursday night raid in the city of Guangzhou. The commission also said it was cracking down on other car-hailing apps in the region and issuing fines of 30,000 yuan, or about $4,860.

Uber said in a statement Friday that it was cooperating with the authorities while continuing to offer the service to Guangzhou residents.

The transport commission said it recognized the limits of traditional taxi services in the area and was studying how online-based services could fill the need.