The Yahoo Mail accounts of a number of Chinese journalists and opposition political activists may have been compromised earlier this week, in an attack reminiscent of the one that targeted Gmail accounts in January.

The New York Times reports that "the infiltrations, which involved Yahoo email accounts, appeared to be aimed at people who write about China and Taiwan, rendering their accounts inaccessible, according to those who were affected. In the case of this reporter, hackers altered email settings so that all correspondence was surreptitiously forwarded to another email address."

The paper also notes that the website of a Chinese human rights organization was attacked and taken offline by hackers for the fifth straight day.

Reuters reports that the World Uyghur Congress, a foreign-based political activist group that the Chinese blame for inciting separatism in Xinjiang, was also the victim of a cyber attack. A spokesman told the news agency that "I suspect a lot of information in my Yahoo account was downloaded."

Experts say that the seemingly frequent controversies around internet use in China could make search engine optimization (SEO) efforts in the country less effective.