Websites cut off as rumours spread in the wake of Bo Xilai's removal. Chinese internet users found themselves unable to connect to even the most mundane foreign websites, while people outside China reported they could not access Chinese sites. The world's largest internet population, some 500 million people, had been walled in. The incident prompted speculation that the Chinese government is testing a system to shut down the internet in the event of a political emergency. The best guess is that they were upgrading the Great Firewall and something glitched. The Great Firewall is the censorship shield that keeps foreign websites such as Facebook and Twitter out of China. An internet company in the city of Shenyang in the north-east of the country said it had been informed that there would be an outage while portals admitting content from outside China were "regulated." It said the action was linked to the 18th Party Congress, the moment this autumn when China will unveil a new set of leaders. Before the power transition, the government is determined to maintain a firm grip. After Mr Bo's removal from power, rumours of a coup d'etat have swept through the Chinese internet, panicking the Communist party. Yesterday Xinhua, the state news agency, said it had shut down 42 websites and deleted 210,000 messages since March for containing "rumours." At the weekend, China Central Television, the official broadcaster, said that the internet had "provided space for some people to make up and spread rumours."