The US has complained officially to China over its strict new internet censorship rules as tension builds over an issue causing consternation among international technology companies and Chinese internet users.
The development is a rare direct intervention by the US over internet freedom, which has steadily risen in importance as an issue between the two countries in recent years, in part because US technology companies see censorship as a back-door way of keeping them out of the Chinese market.
China has ordered PC makers to load internet filtering software from a Chinese company, Green Dam, on all machines that go on sale from July 1. Though officially directed at filtering out pornographic material, the order has raised concerns that it could give officials a far more powerful tool for blocking political content.