The instant messaging service WhatsApp has been disrupted in China as the government tightens security in the run up to a Communist Party meeting.
Services started going offline more than a week ago, the BBC has reported. The disruption comes ahead of the 19th National Congress of the Communist Party of China, to be held in Beijing next month.
At times WhatsApp has reportedly been completely blocked and only accessible to users via virtual private networks (VPNs) which bypass China’s internet firewall.
The app is the only Facebook product allowed to operate in mainland China.
BBC correspondents in China have been reporting problems with WhatsApp, while tests of its services on Tuesday showed users in China could not send messages, video or pictures to people outside China.
The tightening of online censorship comes as China steps up security ahead of the Communist Party's national congress in October. The meeting is held every five years.
"The run-up period to a gathering is normally a time of greater restrictions of all kinds to assure that the critical Party Congress is held under ideal social conditions and is not disrupted", Robert Lawrence Kuhn, long-time advisor to China's leaders and multinational corporations told the BBC.
However, he said it is not yet clear whether the restrictions will be relaxed as has happened after previous party congresses, adding that many analysts do not believe they will be.
Messages sent on WhatsApp are automatically encrypted, meaning only the sender and recipient can access their content.
"China has shown little tolerance to encryption especially on platforms that can be used to share materials or potential propaganda," Bill Taylor-Mountford, Asia Pacific vice president for LogRhythm told the BBC.
The disruption comes as China appears to crack down on online content. On Monday, its cyber watchdog handed maximum penalties to some of the country’s top technology firms for failing to properly censor online content.
