China’s state news agency called for internet sites to quell the “cancer” of online rumors on Tuesday, the latest sign of the government’s unease over the growing popularity of social networking sites, AP reported. “To nurture a healthy internet, we must eradicate the soil in which rumours grow,” Xinhua wrote in the commentary, which was published only in Chinese and came just days after a similar recommendation from a senior Communist Party official. In recent years, the rise of weibos – microblogs similar to Twitter – have made blocking politically sensitive content from China’s 485 million internet users increasingly difficult. Officials seemed to be taken by surprise this summer when a train crash that killed 40 prompted Sina (SINA.NASDAQ) Weibo users to send millions of messages criticizing the government’s response to the disaster. Shortly after the incident, the state media outlet People’s Daily urged officials to use weibos to communicate more with the public.