Attempts to search Weibo for “the truth” on Thursday turned up the message: “According to relevant laws, regulations and policies, search results for ‘the truth’ cannot be displayed.”

It is not known how long the term has been blocked or why but one internet-user said they had first noticed the truth was missing in late June. Sina Weibo did not respond to requests for information.

Qi Zhenyu, head of social media for iSun Affairs, a Hong Kong-based current affairs magazine, said it was not clear when censors might allow the truth to return.