<p>January 22, 2013, 2:48 AM China's censors have started blocking access to software collaboration site GitHub, and Internet observers are speculating the government's efforts to regulate the nation's online train ticketing system are to blame.</p><p>GitHub has confirmed that its site was at least being partially blocked in China, and is investigating the matter, spokeswoman Liz Clinkenbeard said via email on Tuesday.</p><p>The blocking may have started as early as last Thursday, leaving the site partially inaccessible, according to GreatFire.org, a group that monitors China's Internet censorship. But by Monday, the site had been completely blocked, the group added.</p><p>GitHub is best known as an online repository for open source projects, letting developers share code. Its site has 3 million users, and China ranks fourth among the top ten countries that visit GitHub. Among the top ten cities, Beijing ranks number six.</p><p><a href="http://www.itworld.com/software/337550/github-blocked-china-ticket-snatching-plugins-seen-possible-cause">Keep reading...</a></p>