56.com, a leading Chinese online video site, has been offline since June 3rd, and though the official explanation is server upgrades, it’s widely believed the site ran into trouble with government regulators. 56.com was among a group of top Chinese video sites that were recently denied licenses from the Chinese government to share video online.

This isn’t the first time a Chinese video site outage has raised questions of censorship. In March, Tudou.com was reportedly shut down by Chinese officials for hosting inappropriate content, though the site denied it received any such order.

At the start of the year, Chinese regulators said that video sites would have to be state-owned. The government later clarified its list of requirements for video sites, including the types of content that must be filtered. The strict regulations leaves the state of the online video business in China in flux.

China is home to a booming Internet population, currently estimated at 225 million users. A government survey reported that 77 percent of those users watched online video last year.