As Facebook prepares to go public it has its sights on China, where the social media titan is blocked, but analysts say its chances of re-entering the market of half a billion internet users are slim.

Facebook, which filed paperwork seeking to raise $5 billion on Wall Street, said it continued to evaluate entering China – the world’s largest internet market and a huge dark spot on Facebook’s global map.

“There are more than two billion global internet users and we aim to connect all of them,” the California-based company said in the listing documents filed with the US Securities and Exchange Commission.

Facebook, which has more than 800 million users around the world, is the leading social network in all but six countries, notably Russia, where local rivals are preferred, and China, where it has been banned for years.

Beijing blocked Facebook along with micro-blogging site Twitter after blaming it for fanning social unrest in the northwestern region of Xinjiang in 2009, though many web users access the site via virtual proxy networks. Prior to the ban, web users in China enjoyed uncensored access to Facebook.

In the run-up to a major leadership transition later this year, experts said Facebook has next to no chance of being allowed to operate freely in China, unless it is willing to bow to the country’s army of censors.

“Under the current political structure it has probably zero to nil chance of operating in China again,” said Bill Bishop, a Beijing-based internet consultant and investor.

Anne-Marie Brady, an expert in Chinese politics at New Zealand’s University of Canterbury, agreed, saying the only way Facebook could re-enter China was if it followed the same censorship requirements as Chinese-based websites.

Despite the hurdles, Facebook Chief Executive Mark Zuckerberg is clearly keen to see his company crack the Chinese market, which has more than 500 million users, nearly half of whom use weibos, which are similar to Twitter.

Mr Zuckerberg said previously that he was spending a lot of time studying Chinese and visited the country in December 2010 with his girlfriend Priscilla Chan, when he met with the head of the country’s biggest search engine Baidu.

Beijing attempts to block content it deems politically sensitive through a censorship system known as the “Great Firewall of China”.