According to reports, the Yahoo Inc accounts of at least three journalists and an analyst became inaccessible over the last few weeks.
They were greeted with messages saying, "We've detected an issue with your account " and were told to contact Yahoo.
When contacted, Yahoo technicians said one of the four account had been hacked and restored access then.
However, there is no clear information on the exact relation of the Yahoo accounts with the past instances.
This has put a large question mark on the existence of the foreign sites in China over the internet safety issues.
Earlier, Internet giant Google had stopped censoring search results in China over a series of cyber attacks and complaints about censorship.
Later, Google had redirected its Chinese users to the unfiltered Hong Kong site.