Chinese authorities have reportedly blocked the services of messaging application WhatsApp in preparation for its major Communist Party congress billed for 18 October.

Reports say users in Asia’s most powerful nation have reported widespread disruptions in recent days to the application service, which previously malfunctioned in the country on August. Experts said the problems began on Sunday, but text messaging, voice calls and video calls appeared to be working again yesterday (Tuesday), though, voice messages and photos were not going through.

WhatsApp provides message encryption technology that likely does not please Chinese authorities, who closely monitor and restrict cyberspace through their ”Great Firewall”.

According to AFP, many Chinese activists favour WhatsApp over local messaging apps because of its end-to-end encryption function.

China has tightened online policing this year, enacting new rules that require tech companies to store user data inside the country as well as imposing restrictions on what is permissible

”It smells like Party congress pre-emptive blocking,” said Jason Ng, who researches China’s Internet at the Citizen Lab at the University of Toronto.