Unidentified Chinese hackers have reportedly been spying on the Yahoo email accounts of journalists, activists and human rights groups for at least a week.
More than a dozen individuals have been targeted in the latest attacks, including New York Times journalist Andrew Jacobs, who reported on his experiences.
In Jacobs' case, hackers altered the settings of his Yahoo email accounts so missives were surreptitiously forwarded to an email address owned by the hackers.
Irish Times and Independent journalist Clifford Coonan said he had also been targeted, as had freelancer Kathleen McLaughlin.
Other targets reportedly include a law professor, an Uyghur exile, an analyst who reports on China's security systems, and local print journalists.
Google, which recently stopped censoring search results in China over the objections of the government, said it chose to do so in part because it had been deflecting cyber spying attacks originating from China for nearly a year.
Meanwhile, Google has said it had identified a fresh wave of cyber attacks linked loosely to China, but unconnected to its spat with the government over censorship.
The latest attacks are motivated by a dispute in Vietnam over the government's decision to export bauxite to the Central Highlands region via a partnership with a Chinese state-run company.
The attackers have created a botnet which could potentially consist of tens of thousands of computers, which is being used to monitor their owners' input and attack blogs containing messages opposing the plan.
The malware specifically targeted Vietnamese computers, and was transmitted through software including Vietnamese keyboard language software, Google said.
Security company McAfee confirmed the attacks and their political motivation, saying it believes the culprits could have connections with the Vietnamese government.