China has recently cut off access to South Korean portal Daum after blocking access to blogs and cafés on top portal Naver last October.

According to sources in Beijing on Sunday, users in China have not been able to access Daum from Beijing, Shanghai and other key areas. 

The sources said Chinese users can only access Daum with a virtual private network, or VPN. 

The move comes as Chinese authorities have been blocking or restricting online sites both at home and abroad as part of efforts to strengthen control over the flow of information. 

In 2014, China blocked access to top Korean mobile messaging applications KakaoTalk and Line.

Popular online services, Google, Facebook, YouTube and Twitter are also blocked in China.