(CNN) -- China's hugely popular social media app WeChat appears to have been hit by a censorship crackdown.
A number of public pages on the microblogging service -- many of which were maintained by prominent activists -- went dark late last week, some permanently.
Users attempting to access at least 40 WeChat pages have been greeted with 'account-deleted' messages that explained the accounts had been "repeatedly reported" as being in "violation of the rules." Users were advised to unsubscribe from the affected pages.
Pages, such as activist Xu Danei's newsletter, which has around 200,000 subscribers, together with a number of news sites, such as Truth Channel and Phoenix We Media, among others, were affected in the crackdown. The China Digital Times published a partial list of blocked pages.
Government's hand detected?
Some commentators are viewing the move as motivated by the authorities as part of an ongoing crackdown on social media.
WeChat, called Weixin in China, has grown significantly in terms of both prominence and user-base in recent months, as it has become the preferred portal for China's "netizens" to discuss, amongst other topics, politics.
It differs from other Chinese microblogs, such as Sina Weibo, in its use of relatively closed, personal contact-focused networks -- chat groups are usually limited to 40 members. Public pages, such as the ones blocked Thursday, are limited to one post per day.
It is not the first time WeChat has been targeted by censors. Early last year, messages containing characters relating to a newspaper that was pushing for greater press freedom were banned.
Shenzhen-based Tencent, the Chinese internet giant behind WeChat, released a statement on Friday, stating that company does not allow practices that violate laws and regulations. Given the political nature of the majority of blocked pages, this is understood to refer to laws banning the dissemination of political "rumors."
Liu Shengfei, a lecturer in Sun Yat-Sen University in Guangdong Province, had his TeachingRoom public page blocked. The account was used to distribute academic articles.
"I think (this news) will bring negative effects for Tencent," he said. "The articles we distributed on WeChat were being checked before (going) public, which means those articles are legal to be seen. While Tencent blocked us, we were furious with Tencent for going back on their word."
He added that he thought Tencent's credibility would now be tested.
WeChat has been touted as an alternative to rival Sina Weibo, which has seen scores of users defect to the micromessaging app. The Twitter-like Weibo was the target of anti-political rumor laws last year, and as trust in its impartiality was eroded, users took flight. Ironically, following last week's page shutdown, some users have turned back to Weibo to complain about WeChat.
Social media apology
Zhang Jun, Tencent's Chief Public Relations officer, took to social media to issue an apology, accepting blame for the blocking of the pages.
"Many friends devoted a lot of time and energy (to) setting up these public accounts, (which were suddenly) blocked... I am making apologies here if my tone was not right. "
Tencent's flagship product is approaching 300 million active users around the world, most of whom are based in the Chinese mainland, although an increasing number of users are signing up from abroad.
As the blocked pages extended to users worldwide, is not clear if the incident will impact Tencent's global expansion ambitions.
CNN's Serena Dong in Beijing contributed to this report.