Facebook-owned messaging service WhatsApp has been largely disrupted in China before the government organises the Communist Party meeting in October, The New York Times reported. The service is Facebook’s only product to function in mainland China.

Users have reported that the service has either been completely blocked or has only been accessible via virtual private networks that avoid Beijing’s internet firewall. Observers said that several restrictions would be imposed in the run up to the Communist Party’s national congress, which is held every five years, BBC reported.

The Mark Zuckerberg-led company’s main social media service, Facebook, has been blocked in the country since 2009 and photo-sharing app Instagram has also been banned. Facebook refused to comment on the matter, The New York Times reported.

Meanwhile, China’s cyber monitoring agency issued penalties to several major technology firms in the country, including Tencent, Baidu and Weibo, for their alleged failure to restrict objectionable content online, BBC reported.