Beijing, July 21 (IANS): WhatsApp users in China were still experiencing service disruptions on Friday after four days of problems.

Users had first reported problems in sending photos and videos on Tuesday, leading some analysts to believe that Chinese censorship authorities are attempting to control content shared on the service.

GreatFire.org, an NGO which keeps track of internet censorship in China, confirmed to Efe news on Friday that normal service had not yet been restored.

WhatsApp, which is owned by Facebook, was one of the only foreign social media applications that was still operational in China.

China has its own instant messaging service, namely WeChat, which collaborates with the country's censorship authorities to erase messages and accounts with "sensitive" political material, unlike WhatsApp, whose messages are encrypted.

The service disruptions have been reported in the same week that Nobel Peace Prize laureate Liu Xiaobo passed away.

Liu was also a victim of Chinese censorship, as all references to him on social media and websites were either blocked or deleted by the authorities.

Chinese censorship authorities have even blocked tributes to the writer and deleted photos of empty chairs posted by his followers as a symbol of the Chinese dissident.

China has blocked access to websites like Google, Facebook, Twitter and YouTube for years, which has led to the rise of local equivalents and contributed to the emergence of Chinese online giants including Baidu, Alibaba and Tencent.