The US government has described China's internet controls as a barrier to trade in a report which coincides with attempts by Beijing tries to block the public from seeing news about the finances of Chinese leaders' families.
A US trade representative said Chinese filters, which block access to websites including Google and Twitter, are a "significant burden" for businesses.
The report does not indicate whether Washington plans to take action, but it highlights complaints that Beijing's controls hamper access to its large internet market and disrupt operations for foreign companies.
This week, Chinese censors have tried to block internet users from seeing news reports about leaked documents relating to a law firm in Panama which say relatives of political figures, including president Xi Jinping, own offshore companies.