Hong Kong protests' 'Umbrella Revolution' tag escapes China's censors - so far

China's censors, who have barred most online discussion of the pro-democracy protests in Hong Kong, have so far not blocked searches for the movement's "Umbrella Revolution" nickname, although it may not survive much longer.

Chinese Internet users were still able to post under the hashtag "Umbrella Revolution" in Chinese and English on Sina Weibo, China's popular Twitter-like microblogging service, on Monday and Tuesday.

China blocks popular foreign sites like Facebook, Twitter and YouTube, fearing the uncensored sharing of images and information among the nation's more than 600 million users could cause social instability.

Umbrellas became the symbol of the Hong Kong movement after tens of thousands of protesters used them to shield themselves from pepper spray and tear gas fired by police on Sunday.

Colourful representations of umbrellas have since sprung up on social media around the world, including on Sina Weibo where users often abbreviate words like Hong Kong and Beijing in an apparent bid not to attract the attention of censors.

"Facing a strong opponent, we can only use umbrellas!" said a user on Sina Weibo.

Another said: "Let BJ see the light #umbrella revolution#", in an apparent reference to Beijing.

Others found creative ways to jump what has been dubbed China's "Great Firewall", the cloak of Internet security used to block access to things authorities deem too sensitive.

"Ti*n*men Echoes: H*ng K*ng," said a user on Sina Weibo, referring to Beijing's bloody crackdown on pro-democracy protests in Tiananmen Square in China's capital in 1989.

It was unclear why the "Umbrella Revolution" search remained open on Sina Weibo while it was blocked on Tencent Weibo, another popular microblogging service.

On Sina Weibo and Tencent Weibo, search results for "Occupy Central", a catch-all phrase for the Hong Kong protests, showed a page that said "according to relevant laws, regulations and policies, search results are not displayed".

On Sunday, users reported that Facebook's photo sharing app Instagram was inaccessible on the Chinese mainland.

King-wa Fu, assistant professor at the University of Hong Kong's Journalism and Media Centre, said it was likely censors had not yet realised the popularity of the phrase "Umbrella Revolution", which was coined by international media.

"It takes time for the censors to recognise that the umbrella has some special meaning, referring to 'Occupy Central'," said Fu, who runs WeiboScope, a project that analyses censored posts in China. "I think it's just a matter of time, today or tomorrow. Umbrella will become a sensitive word," he told Reuters.

Chinese media has largely limited its coverage of the Hong Kong protests to government condemnations and state-run media has published few photos of the protests.

Data from China's top search engine Baidu showed that the search volume for "Occupy Central" jumped more than 20-fold between Friday and Sunday.