Chinese web giant Tencent has denied claims that there is global censoring of its popular chat app WeChat.
It said a technical glitch had led to certain sensitive terms being blocked outside China.
Tech blogs Tech in Asia and The Next Web both reported receiving messages saying their chat entries contained "restricted words".
But one analyst told the BBC it was unlikely that the issue was just a "passing glitch".
The blogs said their entries were blocked.
The Chinese government is known to closely monitor internet traffic within China, and all web content that crosses the state's borders.
China's Great Firewall prevents a number of Western companies such as YouTube, Google+, Twitter, Dropbox, Facebook and Foursquare from operating inside the country. The authorities also demand self-policing from local websites.
When approached by Tech in Asia, Tencent issued a statement, saying: "A small number of WeChat international users were not able to send certain messages due to a technical glitch [last] Thursday.
"Immediate actions have been taken to rectify it. We apologise for any inconvenience it has caused to our users.
"We will continue to improve the product features and technological support to provide better user experience."
But Tom Rafferty of the Economist Intelligence Unit told the BBC the issue was unlikely to be just "a passing glitch", and said that such practices could pose technical and political challenges to Tencent because international users were accustomed to sharing information freely.
"The latest incident... is representative of the 'growing pains' that China's internet and social media companies are likely to experience as they expand globally," he said.
"The servers of such companies are typically based in China, which means the traffic they process will always potentially be vulnerable to monitoring.
"It goes against the grain of domestic censorship regulations, which show no clear signs of being loosened.
"Domestic users, many of whom already baulk at the level of censorship imposed on them, would react unfavourably if Tencent were to offer unfiltered content to overseas users."
According to Tencent, whose services include instant messaging service QQ, microblogging site Tencent Weibo - which is similar to Twitter - and online games, WeChat has close to 300 million users.
That makes it one of the world's biggest messaging apps.