The Chinese authorities are believed to have blocked a majority of domestic users from accessing Google.com.
Press freedom group Reporters Without Borders claims that internet users in major Chinese cities have had difficulty accessing Google's international site for the past week.
However, Google China, which blocks politically sensitive material to comply with government censorship rules, is not experiencing any such difficulties, according to Reporters Without Borders.
"It was only to be expected that Google.com would be gradually sidelined after the censored version was launched in January," said the organisation in a statement.
Cui Jin, a spokeswoman for Google in Beijing, insisted that the situation is being investigated.
Found by calculating the strength of the material deep inside the crust of neutron stars
Can highlight in real-time the relevant regions of an image being described
Double legal trouble for Musk as he also faces civil lawsuit over renewed British pot-holer 'paedo' claims
Battery development could help boost performance of smartphones