Chinese social networking and microblogging sites that provide services similar to Twitter have reverted to test mode or proved difficult to access amid a seeming clampdown from government authorities.
Sites such as NetEase.com Inc's microblog (t.163.com) and Sohu.com Inc's microblog (t.sohu.com) were each inaccessible at least one day this week. All messages on Sohu now display the notice "in testing mode," Reuters reported.
Twitter itself is banned in China, but other microblogging services allow users to post short messages and follow other users.
The Shanghai-based Oriental Morning Post said the websites were under pressure from Chinese censors, Reuters reported.
"Nobody will publicly announce the reason, but it is as obvious as a fly on a bald head," one company source told Reuters, declining to be named because of the sensitivity of the matter.
Chinese Social Media Sites Closed Amid Seeming Clampdown