China had already banned Twitter in 2009, but it had its own internet companies providing microblogging services that allowed users to post frequent updates and follow other posters.
NetEase.com Inc's microblog was inaccessible in China on Wednesday, Jul 14, a day after its services went down and had gone under maintenance.
All Chinese Twitter clones including Sohu.com Inc's microblog displayed the notice "in testing mode".
News content on Chinese Internet websites is under intense government censorship, and online news editors with major Internet portals often receive diktats from the government on what can and cannot be published.
But the new microblogs of Internet portals, with less government censorship, had proved to be freer for carrying news and comments.
Beijing had been trying to tighten controls on the country's booming Internet industry, the world's largest by users, since the second half of 2009, introducing new regulations concerning online gaming, online mapping and e-commerce.
"NetEase's micro-blog is very popular and growing fast, so we had to perform maintenance to upgrade features," said NetEase spokesman Liu Youcai denying the government pressure on the issue.