Mainland authorities have boosted their cyberspying capability by developing technology that can track communications in the languages of ethnic groups.
The sophisticated new system will allow the monitoring of voice calls, text sent via the internet and even communications embedded in images or graphics to alert them to possible social unrest.
The system is aimed at local authorities in areas such as Xinjiang and Tibet , where security officials do not know the local language. But rights groups warn that the technology could lead to the further suppression of minorities.
Ding Xiaoqing, a professor at Tsinghua University's Centre for Intelligent Image and Document Information Processing, and the leader of the team behind the new application, said most government officials in ethnic regions are Han Chinese who cannot read or speak the local language.
"With the help of our technology, they can have first-hand, real time access to intelligence information. They can also deal with multiple languages with one system," she said. The technology can translate every major ethnic minority language in China, Ding explained.
To broaden its use, the team had included overseas languages such as Arabic and Japanese.
Ding said a more comprehensive surveillance approach could detect valuable information currently going unnoticed.
She pointed to the recent suspected terrorist attack at Tiananmen Square on October 28, in which five people died and 38 were injured.
Beijing blamed the violence on Xinjiang separatists. But a more robust system might have picked out warning signs, Ding said, especially those encoded in images.
"An increasing number of messages are passed around on the internet in image format to dodge the government's surveillance. Most of the equipment in use these days cannot deal with such information," she said.
The central government already maintains a vast cybersurveillance system and employs hundreds of thousands of staff to comb through online communications.
It also has the ability to detect the level of "public emotion" contained in non-Putonghua posts or commentaries on the internet and alert authorities to possible outbreaks of unrest.
But the system faces constraints. For instance, it can deal with only a single language, and requires operators who speak it.
International rights groups expressed concerns over increased monitoring.
Eleanor Byrne-Rosengren, director of Free Tibet in London, said technology was already being used to suppress free speech and the distribution of information about Tibetan issues over the internet.
"A Tibetan teenager was arrested earlier this year for having Tibetan loyalty songs on his phone - apparently in a random, physical check.
"We also know that Tibetans have been arrested and questioned regarding specific content [kept in a digital format], implying that electronic surveillance directly prompted the police action," Byrne-Rosengren said.
"New forms of technological surveillance are certainly a matter of concern - sharing information by electronic means has already led to significant jail sentences - and we will be monitoring developments closely."