Microblogging activity in China fell in 2013 compared with 2012, a Chinese report said, possibly reflecting a recent government censorship crackdown and growing competition from mobile messaging applications.

The total number of users of Chinese microblogs, like Sina Corp.'s (NASDAQ:SINA) Weibo, fell from 308.6 million in 2012 to 280.8 million in 2013, according to a report from the government agency China Internet Network Information Center. The agency attributed the 9 percent drop to growing competition from social networking and mobile messaging applications on smartphones, such as WeChat, the Wall Street Journal reported on Thursday.

But another possible cause, which the report does not mention, may be the Chinese government’s crackdown on microblogs, which have given many Chinese -- dissidents or just disgruntled citizens -- a platform to voice their opinions on a range of issues, from government corruption and environmental degradation to sports and pop stars. Many controversial news items and topics were widely shared on Weibo; many use the platform to comment before government censors quickly shut them down.

The campaign has led to the warning and arrests of high-profile bloggers and commentators, and many analysts have warned that the crackdown may dampen microblog use.

The report did not specify its data collection methods, or which microblogs were studied. Between June and September of 2013, Sina Corp. said daily active users for its Weibo service, the largest microblogging platform in China, grew 11.2 percent to 60.2 million, and a Sina spokesperson said the numbers in the new report didn’t match statistics from the company’s most recent earnings. The spokesman added that no organization had been in contact with it about collecting statistics on its user base, according to the Wall Street Journal.

Despite the opaque source of the report’s data, it is still a strong indication that users are shifting from Weibo to newer social media platforms using smartphones. At the end of September, WeChat had 272 million monthly active users, more than double of what it had just a year earlier.

Conversely, the report said the total number of Chinese Internet users continued to grow. In 2013, the nation added 54 million users for a total of 618 million users, compared to 564 million in 2012. In addition, 73 percent of Chinese Internet users were getting online access through their mobile phones, and the total number of mobile Internet users rose to 500 million at the end of 2013, from 420 million at the end of 2012, according to the Wall Street Journal