Shanghai, China - Dramatic images of protesters in Hong Kong wearing face masks and carrying umbrellas to protect themselves against clouds of tear gas have been circulating on media outlets and social media networks worldwide.

Except, that is, in China.

While Twitter, Facebook, Instagram and other social media networks have been flooded with images of what is now being called the "Umbrella Revolution", the censors in China have been working overtime to ensure the flow of information is carefully controlled there. Twitter and Facebook are already blocked in China, and Instagram is the latest social media network to be severed, most likely due to the high volume of photos from the protests being posted.

"Charlie Smith" - the cofounder of the website greatfire.org, which monitors internet censorship in China, and who uses a pseudonym to protect his identity - said Instagram was blocked in China "because of photo sharing" in relation to the protests.

Although many international social media sites have been stifled, domestic Chinese social media such as microblogging site Weibo are hugely popular. However, they are tightly monitored and mentions of any sensitive topics are routinely deleted or edited. Weiboscope, a project that monitors censorship at the University of Hong Kong's Journalism and Media Studies Centre, found many posts relating to the protests in Hong Kong have been deleted. The project uses programming tools to monitor the Weibo activity of 50,000-60,000 microbloggers, and graphs the result on a chart on its website.

"In the past three days, you can see quite a large number of censored posts on the chart," said Fu King Wa, an assistant professor who runs the project. "The majority of censored posts are related to Hong Kong."

"Police" and "justice" were also among the top keywords censored.

'Timing awful for Beijing'



Greatfire's Smith said this sort of censorship is common around events considered sensitive by the Chinese government. "In general, the censors at Weibo have to keep an eye on anything protest-related. So regardless of whether or not they had received unusual orders on Hong Kong, they would have deleted many of the photos of the protests without being told to do so."

But Smith added there was a good chance that specific orders were given to prevent the flow of information on the events in Hong Kong.

"The timing is awful for Beijing - tens of thousands of mainland tourists plan on travelling to Hong Kong over the National Day holiday [on Wednesday]. They are going to get the rare chance of seeing an ongoing protest firsthand. So I would expect that there will be increased measures to crack down on social media posts, regardless of platform, that describe the ongoing events in Hong Kong."

However, Fu said it will be impossible for the Chinese government to completely restrict information being accessed by mainland social media users. For example, he said he found references on Weibo to the "Umbrella Revolution" - named after the umbrellas used by the protesters, initially to protect themselves from the sunshine, and later from tear gas used by police.

Fu said this reference has slipped past the censors because it is a relatively new term in relation to the protests.

"I think there will be more posts relating to the protests and Occupy Central circulating in China - but in a different way. Some of them will get deleted, but some of them will get through," Fu said. "I don't think the government can stop all the discussion about this."

It is not only social media content that is being controlled. According to the website China Digital Times, a directive was issued to state media outlets to censor mentions of the words "Occupy Central", and to "strictly manage interactive channels and resolutely delete harmful information".

Negative coverage



Mention of the protests in Chinese media outlets have been tellingly muted, consisting of reports on the negative impact of the demonstrations and carefully worded critical editorials.

[The] illegal campaign [has] begun to take its toll on not only the economy but also on social harmony and stability. - China Daily newspaper editorial

The nationalist Global Times newspaper carried a strongly worded editorial describing the protesters as "radical activists". It refered to their "illicit campaign", stating it was "doomed" and will not succeed in calls for greater democracy for Hong Kong. The paper's Chinese version ran a front-page story with the headline: "Hong Kong government fiercely rejects illegal Occupy Central."

And the China Daily newspaper ran a front-page story about how the protest "disrupts life in Hong Kong", saying the daily lives of people in Hong Kong have been disrupted, and stocks in the financial hub "depressed". An editorial in the newspaper said the "illegal campaign" has "begun to take its toll on not only the economy but also on social harmony and stability".

Hong Kong enjoys a much greater level of freedom of speech than mainland China, and social media networks generally are not blocked there.

They have been used by protesters to share information about what is happening, and to mobilise people to join the protests. However, there have been complaints online of an inability to connect to mobile networks where the protests are taking place, sparking rumours that authorities are interfering. There have also been reports of messages relating to the protests being deleted on the Chinese messaging app, WeChat.

In order to circumvent this, protesters have used Firechat, a mobile application, to send messages without being connected to the internet. Instead, Firechat uses Bluetooth to send messages between users. The app has previously been used by protesters in Iraq and Iran - but never before has it been used on the scale of the protests in Hong Kong.